Old Mother Hubbard 2012: The Defensive Tackles

The Old Mother Hubbard series takes stock of what goods the Lions have left in the larder; i.e. the assets they have going forward. We’ll assess each player the Lions will likely bring to training camp. By tradition, we start with the defensive tackles and move away from from the ball. Here’s what last year’s Old Mother Hubbard had to say about each defensive tackle the Lions will be bringing forward:
Ndamukong Suh:

An incredible physical talent, with almost unlimited upside. As a rookie, he performed like an above-average starter, while carrying the heaviest workload in the NFL. If he continues to improve, Suh will become one of the best in the NFL—and maybe one of the best ever.

Sammie Hill:

A natural big body who is slowly fulfilling his top-flight physical potential, Hill will remain a big part of the Lions’ rotation as his technique and body develop.

Corey Williams:

Williams was a two-way force for the Lions in 2010, and an incredible addition to the roster. With his natural size (6’-4”, 320 lb.), great acceleration, and sometimes-too-quick snap anticipation, Williams is a difficult assignment for any offensive lineman. It would be really, really, really nice if he could cut down on the penalties.

Nick Fairley, of course, was not around to OMH, and Andre Fluellen is an unrestricted free agent whose time seems to finally have come. Let’s see how Suh, Hill, Williams, and Fairley stack up against the league high, low, and average:

Ndamukong Suh is the perfect example of why I decided to add Advanced NFL Stats WPA+ and EPA+ data to this analysis. You can see that solid down-to-down run-stuffing combined with few-to-no penalties results in an extraordinarily high PFF grade, as with like the Jets’ Sione Pouha. Though Suh is the highest-graded pass rusher of this group at +8.6 (avg. -0.76), Suh’s overall grade is barely above league average at +3.3 (avg. +2.13).
This describes something true about Ndamukong Suh’s play: his -1.7 rush grade (avg. +2.45) means that most of the game, he’s doing a mediocre job of run stuffing and “pass coverage” (screen-sniffing-out). This is where EPA+ and WPA+ come in.
As Brian Burke of Advanced NFL Stats explains, EPA is a statistic that measures the Expected Points Added on offense: for each play made, how many points is that play worth (in his mathematical model)? Defensively, Burke measures performance with +EPA: he adds up “the value of every sack, interception, pass defense, forced fumble or recovery, and every tackle or assist that results in a setback for the offense.”
+EPA captures the positive impact a player has on his team—his playmaking ability. Generally speaking, the more and more-positive plays a player makes, the better he is relative to players who make fewer plays. To borrow a phrase, this accentuates the positive and eliminates the negative; +EPA can’t possibly measure defensive plays not made (Suh getting trap-blocked out of a play, for example).
There is an obvious connection between +EPA and high overall performance: Sione Pouha has the highest overall PFF grade, and the 6th-highest +EPA. But while Ndamukong Suh ranks 33rd in overall PFF grade, he’s 8th in +EPA. Suh is a “plus player,” to use scout’s parlance; he makes a dramatic positive impact on his team and the game.
Now, we turn to Win Probability Added. Again, Burke:

The model created here at Advanced NFL Stats uses score, time, down, distance, and field position to estimate how likely each team will go on to win the game. For example, at the start of the 2nd quarter, a team down by 7 points with a 2nd down and 5 from their own 25 will win about 36% of the time--in other words a 0.36 WP. On that 2nd down and 5, let’s say there is a 30-yard pass, setting up a 1st down and 10 on the opponent’s 45. Now that team has gone from a 0.36 to a 0.39 WP. The WPA for that play would be +0.03.

EPA+ measures the expected points added by a defender’s positive plays, and WPA+ measures how much more likely a defender’s team is to win a game because of the positive plays he made. It makes sense that there’s a very high correlation between EPA+ and WPA+ (for this year’s DTs, it’s an r-squared of 0.883), but what WPA does is emphasize the game situation. A sack on 3rd and 6 is huge, but a sack on 3rd and 6 when you’re up by three late the 4th quarter is a lot huger than the a sack on 3rd and 6 when you’re up by 14 in the 1st.
So, back to Ndamukong Suh. He’s tied for eighth in WPA+ with 1.09; Pouha is 16th  at 0.86. But wait, how can Suh have had a bigger positive impact on the Lions’ chances to win than Pouha, when Pouha’s PFF grade was literally ten times higher? WPA+ is a descriptive stat; it describes what happened in context—and in the case of defensive players, only describes their positive plays. Pouha was a devastatingly effective run-stuffer this year, and that’s it. He didn’t rush the passer, he didn’t pick off passes, he made tackles whenever they ran near him and didn’t screw up. That’s a formula for very high PFF grade, pretty high EPA+, and very good WPA+; exactly what we see.
There’s been a lot of talk about Suh’s reduced production this season. By PFF reckoning, he went from 11 sacks to 5, and from 48 tackles to 26. That came partially because of his lightened workload: in games he was active, he played 77.9% of snaps (of course, he was suspended for two games). In 2010 that figure was 90.4%.
The missing piece of the puzzle: stats that are not sacks. In 2010, Suh had 24 pressures and 6 QB hits. In 2011, Suh actually had more pressures, 27, and 4 QB hits despite being on the field for 224 (22.5%) fewer snaps. Suh actually had a sack, hit, or pressure more frequently in 2011 (avg. one per 22.1 snaps) than in 2010 (per 24.3 snaps).
Bottom Line: Ndamukong Suh is a fast, powerful pass-rushing tackle who impacts games about as dramatically as any DT in the NFL. His physical tools and competitive drive allow him to make huge plays at critical moments. His habit of taking bad personal foul penalties has come to a head and been addressed. His down-to-down consistency and run-stopping is improving, if slowly. In 2012, he needs to continue developing if he wants to reach his unlimited potential. 
Sammie Hill had a 437-snap workload in 2011, and graded out at +2.5 overall, slightly above average. That’s a step down from 2010, when he received a +11.5 mark. From what I’ve seen on tape, they used Hill as the primary run-stopping tackle this year, and opposing lines are respecting that with double-teams. Hill is still learning how to handle this newfound attention, often getting dominated at the point of attack then using his strength to recover. His run-stopping grade went from +4.1 in 2010 down to +1.5 in 2011.
But like Suh, Hill had a positive impact much bigger than his PFF grade would suggest. His +WPA was 0.72, ranked 21st of 130 defensive tackles (and well above the 0.425 league average). His +EPA was 21.1, ranked 28th and nearly splitting the difference between Suh's 33.1 and the NFL average of 14.5.
Looking at the radar chart above, it's hard not to notice the Lions DTs hugging tightly to the NFL average in PFF grades, but flying way out towards the maximum in EPA+.
This confirms everything we think about the design of the Lions defense: they coach the linemen to get upfield and make plays, at the expense of typical DL responsibilities. Graded by traditional expectations of defensive linemen, they are mediocre. Graded by how they impact the game, they are outstanding. The whole picture takes both perspectives into account.
Bottom Line: Sammie Hill's is a powerful run-stopping DT with surprising athleticism. His role is growing, and his body and technique must scale with the challenge of his new responsibilities. He must learn to anchor against, or split, double-teams in the run game to take the next step.
Corey Williams needed to cut down on the penalties; he did, from 15 flags drawn in 2010 to just 8. However, he also cut down on the pass-rushing effectiveness. He went from a +9.2 PFF pass rush grade in 2010, down to -2.6. While his coverage and run-stopping grades held steady, cutting his penalties half only made him tied with Suh for third-most penalized DT in the NFL. His 0.5 +WPA and 13.8 +EPA closely match the NFL average for those stats, in a system that maximizes those metrics for DTs.
The ridiculous number of flags tossed his way were worth it when he was a dominant two-way player, not so when he's the least-effective pass rusher on the team. This is his contract year; I would not be surprised if 2012 is his last season in a Lions uniform . . . or if 2011 was.
Bottom Line: Corey Williams had an incredible 2011, arguably a better all-around performance than Ndamukong Suh's studly rookie year. But his pass-rushing performance fell off the face of the Earth when he stopped jumping snap counts, and he's still penalized far too often. If he does not recover some semblance of his 2011 form, he should (and will) be replaced.
Nick Fairley was a DT prospect nearly as beguiling as Ndamukong Suh; after the 2010 bowl season he was the consensus No. 1 overall prospect. Questions about his short on-field track record, his struggle with grades, and his off-field choices lingered, as did those about his long-term commitment to excellence. In the short term, it appears "excellence" is what he's all about.
His 236 snaps were just barely shy of PFF's 25% minimum threshold. If you discount that, Fairley was the Lions' top-graded overall defensive tackle in 2011. His pass rush, pass coverage, and run-stopping grades were all nicely positive, though he was assessed three penalties in those snaps, a poor rate going forward.
Fairley breaks the mold for Lions defensive tackles: he is consistently outstanding in every traditional phase of the game, nearly every down he plays. However, his low snap count and his lack of pursuit game have prevented him from generating enough "flash plays" to shine in metrics like +WPA and +EPA. This will change.
Bottom Line: On the field, Nick Fairley was everything the Lions could have asked for. His size, power, and desire to be great showed through every time he stepped on the field. Unfortunately, a foot injury slowed him at the beginning and end of the season. If he can stay healthy, and continue to develop his "country strong" physique, he could be a monster in 2012.
Overall, the Lions defensive tackles look deep and strong for 2012. Suh and Hill retrenched a little in 2011, but in the context of added responsibility. In very limited time, Nick Fairley was no less dominant in the NFL than in college. Corey Williams, though, had a relatively awful year, and the Lions must make a decision about him.
The Lions need three strong tackles to rotate, and a fourth for depth/development. If Williams is no longer a part of the top three rotation, he could be let go in favor of someone younger. Then again, if he's let go Hill becomes the graybeard of the group at 25. The Lions would also then rely on Hill to realize his potential as a dominant one-technique DT. The Lions may want to keep Williams for his veteran presence, if nothing else.
SHOPPING LIST: Nothing needed here, unless the Lions choose to jettison Williams in favor of someone younger/cheaper.

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Old Mother Hubbard: the Defensive Tackles

Let’s start with the good news! First, let me quote the “Bottom Line” summary of last year’s defensive tackles, from last year’s Old Mother Hubbard:

Andre Fluellen is a very versatile, high-effort player only two years removed from being a third-round draft pick. Whether he plays inside, outside, or both in 2010, Flu should get plenty of rotational snaps next season.

Landon Cohen is rapidly developing from a seventh-round flier into a useful rotational DT. While he'll never be a 320-pound line-clogger, he's only 23. If he focuses on lower-body development, improves his leverage, and continues to hone his technique, he’ll be a very nice complement to/backup for/situational replacement of Sammie Hill.

Grady Jackson turned in a B- performance in doing exactly what the Lions asked—stop the run on 1st and 10. Even if the Lions draft or sign a three-down starter, Jackson can still contribute in that role. I expect to see him back on the roster in 2010, though hopefully not as a “starter”.

Sammie Hill is already the Lions’ best defensive tackle, and should prove to be much better in 2010 and beyond. He has the size, strength, and athleticism to become a perennial Pro Bowler, and his steady improvement from preseason to the end of the season shows the effort and coachability he’ll need to get there. He’ll start for the Lions this season, and for many more to come.

Bottom Line: There’s no doubt that the defensive line is much stouter this season than last—that 0.72 YpC improvement in the run defense had to come from somewhere!—this is still a D+/C- line. The Lions absolutely must add an impact starter. Whether that is an elite DT talent in the draft—as in, with the #2 overall pick—or, by trade for a veteran starter, or by making a splash in the free agent market, it must be done.

There was a lot of praise for each individual player, but the Bottom Line for the unit as a whole said it best: “This is still a D+/C- line.” The Lions needed more consistency against the run than Jackson or Hill were managing, and much more penetration up the middle than Fluellen or Cohen were providing. They needed someone to demand double teams inside, to free up the ends outside.

Subtractions:

Grady Jackson was released after one year in Detroit. Landon Cohen didn’t quite make the final 53 for 2010; he was let go just days before the season opener.

Additions:

Ndamukong Suh, or course, was the Lions’ top draft pick, #2 overall. The Lions traded a fifth-round pick to the Browns for Corey Williams and a seventh-round pick. This is what is technically known, to people in the industry, as a “filthy steal.”

Chart?

Chart.

This is a star chart, showing the Pro Football Focus player grades Of the Lions’ four active-roster DTs. If you’re unfamiliar with PFF’s grading methodology,  just follow that link. They painstakingly review every player’s performance on every snap in every game, grading their performance on each play from –2 to +2, where “zero” is a typical, “he did his job” level of performance. For context, I’ve included the best- and worst-graded DTs who played at least 25% of their teams’ snaps: the Bills’ Kyle Williams, and the Colts’ Daniel Muir, respectively. The black line shows the league average.

First, we see just how ridiculously good Kyle Williams graded out this year, especially against the run; he was nearly unblockable. This was a good chunk of the reason why the Lions’ runningbacks couldn’t get to the line of scrimmage, let alone past it, when they played the Bills.

Though he played just 372 snaps, Sammie Hill graded out as the Lions’ most effective overall DT, and eleventh-best in the NFL. He was the Lions’ best, and most consistent, run stopper. Hill also went the whole season without a penalty, the cleanest of the Lions’ DTs. Surprisingly, he was also an above-average pass rusher.

Initially, Hill’s performance was underwhelming. He turned in weak grades throughout the beginning of the season, especially against Minnesota. However, after the Jets game Hill turned a corner, and graded positively against both the run and the pass for the rest of the season. His best performance was against Tampa Bay: he played about 40% of snaps, and logged a sack, three tackles, and an assist. I admit, I winced when I re-read my line from last year about Hill having the talent to be a “perennial Pro Bowler,” but his upside is high, indeed—and he’s getting there fast.

Bottom Line: A natural big body who is slowly fulfilling his top-flight physical potential, Hill will remain a big part of the Lions’ rotation as his technique and body develop.

Ndamukong Suh played almost a thousand snaps this year, leading all defensive tackles. In the middle of the season, PFF tried to defuse the Suh hype bomb, explaining that his performance was quite rookie-like. Yes, despite undeniable physical talent, and some monster games and plays, Suh was all over the place in 2010. Sometimes, he flashed truly elite pass-rushing skills;  sometimes, he was blown off the ball. Just as I saw with Sammie Hill in his rookie season, Suh struggled against trap and seal blocks. If the man blocking him wasn’t the man directly across from him, Suh was often taken out of the play.

His awesome closing ability means he’s sort of the anti-DeVries: he gets an awful lot of sacks per pressure. However, just as Jared DeVries put a lot more heat on the QB than his sack numbers suggested, Suh’s impacting the game much less than the sack totals would suggest, especially given a thousand snaps to work with.

Let me be clear: a rookie starting, playing a thousand snaps, and getting stronger throughout the year—his best grades were in weeks 8, 11, 12, 14, and 15—is phenomenal. That he successfully brought down the quarterback ten times is amazing. But, remember about the “instant impact” rookie: “amazing” for a rookie is still only “really good” in absolute terms. You can see on the chart above, Suh is nowhere near the best defensive tackle in the NFL. But his floor is “above-average NFL starter,” and his ceiling is . . . well, through the roof.

Bottom Line: Suh is an incredible physical talent, with almost unlimited upside. As a rookie, he performed like an above-average starter, while carrying the heaviest workload in the NFL. If he continues to improve, Suh will become one of the best in the NFL—and maybe one of the best ever.

For all the smart moves, solid trades, and wise decisions Martin Mayhew has made over his two-and-a-half season tenure as Lions GM, none has gotten a higher yield with less of an investment than Corey Williams. By overall grade, Williams was the “least good” of the Lions’ three DTs with enough snaps to qualify for PFF’s rankings. However, that’s almost entirely due to his worst-in-the-NFL grade for penalties, something every Lions fan knows full well about. Williams was the Lions’ best pass-rushing DT, which is saying something; the Lions’ line consists entirely of above-average pass rushing DTs. He was also strongly positive against the run and in coverage.

At the end of the season, Gunther Cunningham said that he thinks Corey Williams is just as deserving of Pro Bowl honors as Suh. Outside of the ridiculous penchant for penalties (several of which kept critical opponent drives alive), the PFF grades agree.

Bottom Line: Williams was a two-way force for the Lions in 2010, and an incredible addition to the roster. With his natural size (6’-4”, 320 lb.), great acceleration, and sometimes-too-quick snap anticipation, Williams is a difficult assignment for any offensive lineman. It would be really, really, really nice if he could cut down on the penalties.

The only other player to earn snaps at DT for the Lions in 2010 was Andre Fluellen. With much fewer snaps than any of the others, he didn’t make the 25%-or-more cut.  He was very slightly above “average NFL starter” level in pass rush, but was a liability against the run. Combined with a picking up a penalty, his final PFF grade put him as far below “average NFL starter” as Ndamukong Suh was above.

Bottom Line: Flu is still very young (two years older than Suh), and has developed into a decent pass rusher. He still has a hard time anchoring against the run, and is more of a “pursuit” guy. He’s not, then, an ideal fit for this defense. But anyone with his frame, athleticism, and ability to penetrate will keep getting chances as long as they keep working hard. Flu is a perfectly fine rotational/situational DT—and still has room to grow.

Practice squadder Robert Callaway, fresh out of Saginaw Valley last season, didn’t see any action. I’m sure the 6’-5”, 312-pound local boy will get at least a camp invite this summer.

SHOPPING LIST? As a unit, the Lions’ defensive tackles are complete. They join the Giants, Eagles, Raiders, and Vikings as the only teams where every member of the active DT rotation was graded above average. The oldest, Williams, is 30; Fluellen just turned 26, Suh and Hill are both 24. Unless the Lions want new blood to replace Fluellen (unlikely, as they just tendered him an RFA offer), the Lions should make no moves here.

Technorati Tags: nfl,detroit lions,defensive tackles,defensive line,nfl draft,nfl free agency,ndamukong suh,corey williams

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The Defensive Line and the Secondary, Part III

Throughout the offseason, it’s been speculated that the Lions’ woeful pass defense will get a boost from the revamped defensive line.  With Kyle Vanden Bosch and developing Cliff Avril on the ends, and Corey Williams and Ndamukong Suh joining Sammie Hill on the inside, the pass rush should be greatly improved.  This should, in turn, take pressure off the unproven secondary . . . right?

I set out to investigate this in part one, using the NFL’s league-wide data over the past two decades or so.  I tried to find correlation between seasons when sacks were up, and seasons when passing offense was down.  I think I learned more from the comments about how statistics and regression analysis work, than I did about the correlation between pass rush and pass defense—but my early results suggested that there is not a correlation between pass rush and pass defense.

I tried again with part two, blending pro-football-reference.com’s official and official-derived data for 2009, with profootballfocus.com’s manually film-reviewed defensive stats and grades.  I came up with a stat I called “pass rush rate,” which was opponent pass dropbacks (attempts + sacks) divided by cumulative sacks, hits, and pressures.  Then, I ran a simple correlation between every team’s pass rush rate for 2009, and their yards-per-attempt allowed.  The correlation was weak, –0.152. When squared to get the effect size, it was a negligible .023.

Importantly, the real-world analysis bore this out: the Jets had an extraordinary pass defense, by far the best in the NFL.  While their pass rush was solid, ranking 9th of 32 in pass rush rate, it was just that—solid, not phenomenal like the overall pass defense was.  Amazingly, the Cleveland Browns generated pressure on the quarterback more often than every team except Dallas and Minnesota—and yet, they were the fifth worst pass defense in the NFL!  Pass rush alone doesn’t make a defense effective.

For this installment, I wanted to get even more specific: I wanted to isolate defensive line pass rush from everything else.  After all, the idea is that getting an effective rush with just the front four will allow much greater flexibility in coverage and blitzing.  I aggregated the stats of just the defensive linemen, and compared them to what I already had.

Now, let me tell you a legendary tale . . . or, well, I guess, just a legend:

• Name: The name of the team.
• A: The primary defensive alignment.
• Pass Rush Rate: The percentage of opponent dropbacks (Attempts + Sacks) on which the defense achieved a pressure stat (Sacks + QB Hits + Pressures + Batted Passes).
• DL Pass Rush Rate: The percentage of opponent dropbacks (Attempts + Sacks) on which the defensive line achieved a pressure stat (Sacks + QB Hits + Pressures + Batted Passes).
• % of rush from DL: The percentage of defensive pressure stats (Sacks + QB Hits + Pressures + Batted Passes) generated by defensive linemen.

NAME	A	Pass Rush Rate	DL Pass Rush Rate	% of rush from DL
Dallas Cowboys	3-4	48.2%	18.2%	37.8%
Minnesota Vikings	4-3	47.7%	38.9%	81.7%
Cleveland Browns	3-4	44.0%	19.1%	43.4%
Miami Dolphins	3-4	43.3%	36.0%	83.1%
Philadelphia Eagles	4-3	43.1%	35.4%	82.2%
New York Giants	4-3	43.0%	35.3%	82.0%
Atlanta Falcons	4-3	42.9%	35.1%	81.8%
Green Bay Packers	3-4	41.6%	13.5%	32.5%
Pittsburgh Steelers	3-4	41.3%	10.1%	24.4%
Houston Texans	4-3	41.2%	32.7%	79.4%
New York Jets	HYB	40.3%	19.3%	47.9%
Denver Broncos	3-4	39.7%	13.1%	33.0%
Tennesee Titans	4-3	39.6%	36.0%	90.9%
San Francisco 49ers	3-4	39.4%	16.5%	41.9%
Washington Redskins	4-3	39.2%	29.2%	74.5%
Carolina Panthers	4-3	39.2%	35.4%	90.3%
Arizona Cardinals	3-4	38.5%	18.7%	48.6%
New England Patriots	HYB	37.8%	18.8%	49.8%
Chicago Bears	4-3	37.3%	29.9%	80.1%
San Diego Chargers	3-4	37.3%	12.5%	33.5%
Kansas City Chiefs	3-4	37.1%	12.8%	34.5%
St. Louis Rams	4-3	37.0%	28.7%	77.5%
Oakland Raiders	4-3	36.6%	30.5%	83.3%
Tampa Bay Buccaneers	4-3	36.3%	29.6%	81.6%
Indianapolis Colts	4-3	35.8%	33.2%	92.8%
Baltimore Ravens	4-3	35.6%	25.2%	70.7%
Seattle Seahawks	4-3	34.2%	27.2%	79.4%
New Orleans Saints	4-3	34.2%	23.6%	69.2%
Buffalo Bills	4-3	32.5%	27.6%	84.9%
Cincinnati Bengals	4-3	32.2%	26.2%	81.3%
Detroit Lions	4-3	29.2%	23.5%	80.2%
Jacksonville Jaguars	HYB	27.9%	10.3%	37.0%

We can see a few things in action here.  First, the Lions were terrible: second-worst in the NFL in Pass Rush Rate.  Second, the numbers get more wildly varied from left to right.  Most teams generate a pressure stat on 30-40% of the time their opponents drop back to pass, with the extremes at 27.9% and 48.2%.  Most teams generate pressure from the defensive line between 15-35% of the time, with extremes at 10.1% and 38.9%.  The percentage of the pass rush that comes from the defensive line is all over the board, from 92.8% all the way down to 24.4%.  What does this mean?

Given the amazingly wide range of percentage-of-pass-rush-from-defensive-line stats, and the zero (okay –.120, R-squared .014) correlation between them and Pass Rush Rate, I knew that scheme was a major factor.  The Colts generated almost all of the pass rush from the defensive line, just as a Tampa 2 is supposed to.  Their two ends, Robert Mathis and Dwight Freeney, accounted for 24 of Indy’s 33 sacks, 23 of 45 hits, 78 of 139 pressures, and 1 of 4 batted balls.  That’s right, Mathis and Freeney were fifty-seven percent of the Colts’ pressure statistics; they were the Colts’ pass rush.  Meanwhile the Steelers, despite having one of the league’s better pass rushes, got only 24.4% of their rush from their line.

  I separated the teams out by scheme, grouping 4-3 teams together, and 3-4 and hybrid teams together.  Since the Lions are a 4-3 team, and that’s what this exercise is all about, I discarded the 3-4s and the hybrids, and set about correlating PRR with Y/A, for just 4-3 teams:

Okay, so these are the 2009 4-3 defenses, and their overall Pass Rush Rate regressed against opponent Yards per Attempt.  Look at the R-squared; there is literally zero correlation between these two statistics.  Okay, we expected that to an extent—but what if we do it for just defensive line?  If the rush is getting there without blitzing, that should make coverage better—so, we should see a tighter correlation when we regress DL-only Pass Rush Rate against Y/A Allowed:

That’s a little itsy bit better, but there’s still no real correlation happening here.  Okay, what if we do it for percentage of pass rush that comes from the defensive line?

Okay, we’re making tiny, tiny incremental progress, but this is still nothing we can call correlation.  Yards per Attempt, my favorite measure of per-play passing effectiveness, is completely disconnected from pass rush, DL-only pass rush, and percentage of pass rush generated by the DL.  But we know for a fact that teams with good pass rushes have good defenses, right?  I mean, the Vikings have a good defense, right?  Right.

Okay, now we’re talking.  In all of my pass rush data mining, the strongest meaningful correlation I could find was between what percentage of pass rush comes from a 4-3 defensive line, and how many points that defense surrendered on the year.  As I said way back in part one:

We're left with the depressing conclusion that the only good pass defense is good pass defense. However, that's not really the case, either. Sacks and interceptions, though they don’t affect the interplay of pass offense and pass defense outside of themselves, are still extremely important in terms of total defense. Stopping drives and preventing scoring is the primary job of a defense; a third-down sack or a red-zone INT can erase sixty or seventy yards’ worth of Montanaesque passing effectiveness.

So again, as I’ve been saying: an improved pass rush won’t improve a team’s pass defense—but it will improve the team’s scoring defense.  Here’s the second-strongest correlation I found: percentage of PRR from a 4-3 DL regressed against Passing 1st Downs Allowed:

Okay, again, this makes sense: the more pass rush you can generate from your 4-3 defensive line, the fewer passing first downs you allow . . . but we’re not done yet.  I calculated the simple correlation factors for every offensive stat I thought might be illuminating.  Note that these are NOT the R-squared effect sizes you see in the charts above—since that eliminates the direction of the correlation, which is important here.  To get those effect-size figures, square the amounts in this table:

Category	%DB/P	%DB/DLP	%P/DL	Att/PD
points	-0.133	-0.360	-0.547	-0.237
total first downs	-0.007	-0.210	-0.431	-0.262
passing first downs	-0.015	-0.241	-0.482	-0.132
running first downs	-0.187	-0.257	-0.232	-0.114
yards per attempt	-0.064	-0.139	-0.190	-0.062
yards per completion	-0.147	-0.316	-0.418	-0.293
completion percentage	0.135	0.269	0.325	0.356
interceptions	-0.133	-0.081	0.037	0.165
touchdowns	0.175	0.205	0.123	0.134
passer rating	0.156	0.148	0.049	0.012

Look at completion percentage: there is a weak, but positive correlation between PRR, defensive line PRR, and percentage of PRR from DL and completion percentage.  So, as the defensive line gets more pressure, generally quarterbacks complete more of their passes—but, at what cost?  Look again at yards per completion; there’s a moderate negative correlation between increased DL pressure and average completion length.

There is a definable “cringe effect!”  When the defensive line generates more pressure, offenses generally tend to complete more and shorter passes—“going into a shell,” as it’s called.  It’s this mechanism, completing more passes for fewer yards, that explains why yards-per-attempt allowed doesn’t change as the pass rush rate increases.  Teams will dink-and-dunk in the face of the rush—meaning they convert fewer third downs, and score fewer points.

So.  How much better will the Lions’ defensive line have to be?  Well, as we saw, their pass rush numbers are terrible.  In order for the Lions to improve their Pass Rush Rate to the league average, they’d have to increase it from 29.2% of snaps to 37.7%.  To increase DL PRR to league average, they’d have to increase it from 23.5% to 30.7%.  The percentage of PRR from the DL is about right, 80.2% versus 81.3%.

The league average team faced 567 dropbacks last year, compared to the Lions’ 571, so I’ll normalize the Lions’ pressure stats to 99.3%: 22.83 QB sacks, 34.76 QB hits, 100.29 QB pressures, and 7.94 batted passes.  I’ll do the same for the DL pressure stats, from 18 to 17.86, from 26 to 25.82, from 82 to 81.43, and from 8 to 8.94.  Now, to compare to the NFL average, find the difference, and voila:

Team/Data	%DB/P	%DB/DLP	%P/DL	QBSk	QBHt	QBPr	BP	DLSk	DLHt	DLPr	DLBP
Detroit Lions (normalized)	29.2%	23.5%	80.2%	22.83	34.76	100.29	7.94	17.86	25.82	81.43	7.94
NFL Average 4-3	37.7%	30.7%	81.3%	33.00	52.00	118.00	10.00	25.00	40.00	98.00	9.00
Delta (absolute)	8.5%	7.2%	1.1%	10.17	17.24	17.71	2.06	7.14	14.18	16.57	1.06
Delta (percentage)	29.1%	30.6%	1.4%	44.5%	49.6%	17.7%	25.9%	40.0%	54.9%	20.4%	13.3%

We can conclude that, in order to bring their pass rush up to NFL average levels for a 4-3, their defensive line will have to increase their sack rate by 40%, their hit rate by 54.9%, their pressure rate by 20.4%, and their batted-ball rate up by 13.3%—and they’ll need a few more sacks and hits from the linebackers and secondary, as well.  I’m still working on projecting all that data out into points allowed, first downs allowed, etc., but there you have it.  If the Lions face the same number of dropbacks in 2010 that the average NFL team did in 2009, the difference between KVB/Avril/Williams/Suh and Avril/Hunter/Cohen/Hill will have to be worth an improvement of 7 sacks, 14 hits, 17 pressures, and 1 batted ball over 2009’s 18, 26, 82, and 8 to get back to average.

Technorati Tags: nfl,detroit lions,ndamukong suh,kyle vanden bosch,defensive line,statistics,sacks,analysis

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The Lions' Defensive Line, As I Understand It

My recent articles about Ndamukong Suh and the Lions' defensive line have kicked up a bit of a fuss about the roles of Suh, DT Corey Williams, and RFA target DT/DE Anthony Hargrove within the Lions' defense. This is my understanding of how all of these players can contribute to the Lions' defense, along with holdovers like Sammie Hill, Cliff Avril, and Jason Hunter.

This is the Lions' base defensive line alignment:

The numbers represent where the defensive linemen line up. You've heard me reference this before: the "one-technique" defensive tackle lines up between the left guard and center, the "three technique" on the outside shoulder of the right guard. In the Tampa 2, these tackles are called the "nose" and "under" tackles, respectively. Though I don't believe Schwartz and Cunningham use that nomenclature, I've labelled the 3-tech and 1-tech as "UT" and "NT" in this diagram for clarity.

In the Schwartz/Cunningham system, the ends line up very, very wide--beyond the outside shoulders of the tackles. This serves several purposes: first, it sets an outside edge in the run game. Runningbacks cannot simply bounce outside of the defensive ends to find daylight; they're hemmed in between their offensive tackles. Also, screens and tosses are much harder to execute. Finally, it forces the offensive line to spread out to protect against the outside speed rush, opening up interior gaps.

Schwartz mentioned before last season started that the defense uses "3-4 principles"; this is what he was talking about. The ends set a hard edge on the outside, funneling runs back to the interior. Unlike a 3-4 set, though, there isn't a two-gap tackle handling the interior--there are two one-gap tackles:

You see right away that all gaps aren't accounted for; that's okay. The ends funnel runs inside, and the tackles take up blockers. If everyone merely does their job, the result is something like this:

The ends are in position to hold the edges, the under tackle has locked up the right guard, and the nose tackle has commanded a double-team. Depending on whether one, two, or zero tight ends stay in to block, the defense has already ensured the runningback must stay inside. What happens once this impasse is reached?

Oh, right, linebackers. If the defensive line is doing its job, the linebackers should be able to clean up the mess. Unfortunately, this requires disciplined linebacker play. If the defensive line cannot stop the run by itself, the linebackers must be in position--or the tackle won't get made.

This is why the Lions need help at defensive tackle. If, in the above situation, the UT overwhelms the RG, then the play is disrupted--and there's no daylight outside. Further, if the NT can gain ground against the double-team, or split it, the play is again disrupted.

This is also why the Lions needed help at defensive end. If the DEs aren't strong enough to hold up at the point of attack, then all the interior disruption in the world won't stop the play. Many Lions fans will ruefully remember many times Shaun Rogers burst up the middle, only for the tailback or quarterback to sidestep him and have plenty of room to run.

Not only would excellent line play obviate the need for the linebackers to play cautious, stay-at-home football, it would keep blitzing lanes open, improving the blitz's effectiveness against both the run and pass.

Now, where to the Lions' defensive linemen fit into the picture?

• Sammie Hill is the 1-technique tackle, labelled as "NT" above. He's a big, beefy, 330-pound DT with some real athleticism. His rookie year, he was primarily a space eater. However, he flashed the potential to become dominant in that role; not just drawing double-teams--demanding them, and making plays anyway.
• Corey Williams was developing into a star in Green Bay as a 3-technique pass-rushing DT. Cleveland thought he'd make a perfect 3-4 end, and gave up a second-round pick to bring him in. Unfortunately, Williams just wasn't a fit for the scheme. He lacked the speed needed pressure the quarterback as an end, and his natural talent is penetration, not containment.
  It's presumed that he'll return to the 3-tech role that suited him so well in Green Bay, and if the Lions make no additions to the line between now and the regular season, he'll be the starter. However, I could see his role changing on obvious passing downs. Hill is not a penetrator, so the 320-pound Williams could slide over to the 1-tech spot, providing a pass rush without sacrificing size . . .
• Kyle Vanden Bosch is the prototypical right defensive end for this defense: 270 pounds, very strong, very tough, difficult to keep off of the quarterback or runningback.  His tenacity, leadership, and—we hope—production should make him the Lions’ best defensive lineman, even best defender, in 2010.
• Cliff Avril’s first two seasons with the Lions have been a tease.  At times, he’s looked like an elite pass rusher in the making--and at times, he’s disappeared.  At 260-to-265 pounds, he’s decidedly undersized as an LDE in this system.  That might be why he closed the season behind 271-pound Jason Hunter on the depth chart . . .
  Avril’s 2010 is going to be crucial to his development.  He has to continue to develop his body to the point that he can drop anchor on the left edge—and he has to prove he can consistently pressure the quarterback.
• Jason Hunter is a developmental prospect, a hardworking special teams standout who was cut from Green Bay when they switched to a 3-4.  Hunter’s got the perfect body type for this defense, but his play has been inconsistent as well.  At times, he’s played the run well, and at times, he’s been easily blocked.  He’s gotten a little bit of pressure on the quarterback, but he doesn’t have the physical pass-rushing gifts that Avril does. 
  In some ways, he’s the mirror image of Avril: an inconsistent natural run-stopper instead of inconsistent natural pass-rusher, both trying to become a 30-snap guy within this defense, each improving at the expense of the other.
• Kevin Carter is a guy who doesn't play for the Lions, but a player whose role in this defense the Lions would love to fill.  As a Titan, the 305-pound Carter was an outsized pass rusher, a three-down force who would play primarily outside, but would slide inside on obvious passing downs to provide an extra push.  It’s this role that would be filled by Saints RFA DL Anthony Hargrove, if he’s traded to the Lions.
  Hargrove's signing would likely relegate Hunter to the bench and special teams (where he arguably belongs, for now), and Avril would continue to rotate in on second and third downs.
• Ndamukong Suh also doesn't play for the Lions, but as you all should know by now, I hope he will.  I think he’s a once-in-five-years prospect as a pass-rushing tackle, a guy that could, in rotation with Corey Williams and Sammie Hill, seriously disrupt opposing offenses—against both the pass and the run. 
  Assuming the Lions do not get Anthony Hargrove, Suh would likely play as the “UT” next to Corey Williams’ “NT” on passing downs—and he could even do a little Kevin Carter on running downs as well.  If the Lions got Hargrove, it wouldn’t necessarily mean the Lions couldn’t draft Suh and rotate him in, just that snaps would be lessened for all involved, and the DL depth would be much,um, deeper.  Picture a nickel-defnese line of Avril, Hargrove, Suh, and Vanden Bosch, or a second-down line of Hargrove, Suh, Williams, and Vanden Bosch, or a first-down line of Hargrove, Willams, Hill, and Vanden Bosch . . .
  Given the news, though, that the Hargrove has signed his tender and the Lions might try to trade out of the #2 pick, the Lions would prefer to trade for Hargrove, move down, and pick up a developmental tackle later.  Who knows if they’ll be successful—for now, though, I don’t think Suh and Hargrove both come to Detroit.

Submitted for your approval: my projected defensive line depth charts with the "Hargrove/Suh" role combined (for now), and rotations/position battles notated, too:

Edited to add: Everyone’s been killing me for not including Turk McBride and/or Andre Fluellen, both of whom got a decent amount of snaps last year and are vaguely promising.  I see McBride (and Andre Fluellen) as occupying the role that I noted here “Hargrove/Suh”.  If either Hargove or Suh were a Lion next year, McBride and Fluellen would be battling for the role of “second-string DE/DT flex". Considering that there are first- and second-stringers at both DE and DT already, there aren’t a lot of leftover snaps.  If both make the team, I think Hunter or Cohen are the casualty.

This is kind of the thing about the Lions getting better—they’re going to let good players go, because those good players aren’t good enough to be on the Lions.  If you add in Vanden Bosch, Williams, and Suh, there are three fewer roster spots to go around for the Marinelli-style four-year projects and ‘tweeners.

Technorati Tags: detroit lions,nfl,ndamukong suh,anthony hargrove,kyle vanden bosch,cliff avril,jim schwartz,gunther cunningham

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Williams, Burleson, Vanden Bosch: Gasoline on the Lions' Little Blue Flame

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Last night, I posted, and we liveblogged, in anticipation—wondering, waiting, hoping.  What would the Lions do?  Who would they pursue?  Would their “selective, aggressive” approach net them real building blocks, stopgap solutions, or nothing at all?  Would we have reasons to jump for joy, and rekindle our hope, or trying to get over our disappointment?  Our impatience was rewarded: we didn’t even have to wait for midnight for the first move.

The Lions sent the later of their two fifth round picks to Cleveland, and in return got Corey Williams, and the Browns’ seventh-rounder.  Williams, a 6’-4”, 320-pound defensive tackle, was a sixth-round pick of the Packers in 2004.  He saw spot duty for two years, then—after notching two sacks against the Lions in 2006—took over the starting job.

Williams garnered 7 sacks in both ‘06 and 07, even being named the GMC Defensive Player of the Week for his 2-sack, 4-solo-tackle, 2-forced-fumble performance against Carolina.  Following a tough playoff loss to the eventual Super Bowl-winning New York Giants, wherein Williams had 4 solo tackles and 5 assists, the Packers placed the franchise tag on Willliams.

However, the Packers traded Williams to the Browns, in exchange for a second-round pick.  Williams was to move from his natural 4-3 tackle position to a 3-4 end spot, flanking fellow 2008 Browns acquisition Shaun Rogers.  Given his big-body size and pass-rusher speed, Williams seemed to be an ideal fit for what the Browns wanted to do.

Unfortunately, Williams simply failed to produce as an end.  Despite starting every game, Williams only managed a half a sack in 2008.  Relegated to the rotation for almost all of 2009, Williams was mostly invisible, but occasionally flashed his old form.  He got his first start of 2009 against Pittsburgh in Week 14—and responded with 5 solo tackles and 2 sacks, leading the Browns to one of the most improbable upsets of 2009.

Corey Williams, at age 29, with seven years of experience, is the kind of foundational veteran in his prime that the Lions have so few of.  With him as a pass-rushing 3-technique (and despite my confusion last night, that’s what he is), and Hill at the 1-tech, the Lions will have 650 pounds of beef in the middle of the line.  That could be the kind of “you won’t run against us” interior the Lions want to build.

Of course, it remains to be seen whether Williams will recapture the form that earned him the Packers’ franchise tag—but, given the pittance they gave up to get him—moving down from the middle of the fifth to the early seventh—it’s a huge win for Mayhew and the Lions.

Nate Burleson is a player I’ve always admired.  When the Vikings were at the peak of their Dennis Green, pinball-numbers, media-fawning-all-over-them, not-winning-anything-ness, Burleson stood out as a smart, tough, talented player who wreaked havoc in the margins between Randy Moss and Marcus Robinson.

In fact, in only his second year since being drafted in the third round, he led the Vikings in receptions and yards (68/1,006), and finished second only to Randy Moss in TDs (9 to Moss’s 13).  This was partially due to him taking over for Moss for a few games when Moss tweaked a hamstring—but production is production. 

Then, there was the whole Poison Pill fiasco.  Seattle, whose All-Pro guard, Steve Hutchinson, had been pilfered by the Vikings—because the Vikings had included a clause that made Hutchinson’s entire contract fully guaranteed if he was ever not the highest-paid offensive lineman on the roster.  Since Seattle was already paying LT Walter Jones more than Hutchinson’s offer, they “couldn’t” match the offer sheet.  In retaliation, the Seahawks signed Burleson to an offer sheet with a clause making the entire contract guaranteed if he played more than five games in one season in the state of Minnesota.

Burleson didn't quite match his 2004 performance in his first year as a Seahawk--but catching 50 balls for 694 yards and 9 TDs wasn’t too shabby.  He showed the burst and open-field moves that a receiver needs in the Bill Walsh offense; he took short passes from Matt Hasselbeck and stretched them out to an average 13.9 yards per catch.

In 2008, the sky was the limit—until Burleson tore his ACL in the season opener, putting him on the shelf until 2009.  He was on pace for an excellent ‘09 campaign, until he suffered a high ankle sprain in Week 13.  Still, he finished with 63 catches for 812 yards and 3 TDs—right in line with his career pace.

When Burleson's healthy, he produces at a pace that’d net him 60-80 catches for a year, at 12-14 YpC.  This is a world apart from Bryant Johnson’s miserable 35-catch, 417-yard performance in 2009.  Moreover, Burleson has the quickness, route-running ability, hands, and toughness to make teams pay for single-covering him with their #2 corner.  He’s the perfect weapon to exploit the aerated coverage he’ll see when playing with Megatron.

With his tough-as-nails approach to the game, and his intelligence, Kyle Vanden Bosch is Jim Schwartz’ kind of player—and Jim Schwartz’s kind of man.  At Nebraska, he was a three-time Big 12 All-Academic selection, and finished his bachelor’s degree in finance with a 3.82 GPA.  He was also Nebraska’s three-time Lifter of the Year.  His 6-4”, 270-pound frame is a prototypical match to Schwartz’s ideal.

Perhaps, then, Vanden Bosch wasn’t surprised Schwartz arrived on Kyle’s doorstep at midnight.  They spent all the wee hours together sharing some vino, and talking some football:

"He said, 'We want to bring you in to be a big-time player,'" Vanden Bosch said. "Not a figurehead. ... He said, 'I watched the tape last year and you're still the same player you were two years ago [when he had 12 sacks for the Titans]. It's just one thing here or there.' ... It was good to hear that again."

The stats, of course, don’t really bear that out: Vanden Bosch had 31 sacks in 2005, 2006, and 2007 combined--but only 7.5 in 2008 and 2009 combined.  Part of that was due to a groin injury robbing him of 10 games in 2008, but as I said before: production is production.

Was Vanden Bosch just a beneficiary of the Titans’ great DT play?  Is he a shadow of his former self?  Will he be a teacher’s pet, a "system guy” whose skills have left him?  According to Tom Kowalski, the answer to those questions is “no”.

Obviously, we’ll find that all out soon enough.  For now, what matters is that the Lions have addressed three of their most important needs: DT, DE, and WR, with veterans who aren’t perfect—but are perfect fits for what the Lions want to do.

The Lions can’t—shouldn’t, anyway—be done.  With the release of Philip Buchanon, the Lions have exactly zero legitimate starting cornerbacks.  The free-agent pickings are somewhat slim there, with only Lito Sheppard catching the eye as a possible step-in-and-start UFA.  There are, however, a few interesting safeties available, and the Lions may yet make a move at left guard.

The National Football Post is reporting that the Lions are in the running for Houston G Chester Pitts, who's a huge, experienced veteran coming off of knee surgery.  Pitts has played both left guard and left tackle, making his versatility a bonus. 

Regardless of who else the Lions pick up--or who else they acquire by trade--today was a huge, huge win for the Lions.  They were selective, they were aggressive, and they made their football team much, much better.  Here’s to more of the same—and a sold out home opener.

Technorati Tags: detroit lions,2010 free agency,2010 offseason,nfl free agency,nfl,kyle vanden bosch,nate burleson,corey williams,cleveland browns,seattle seahawks,jim schwartz

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