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Posted at 10:14 AM ET, 09/21/2011

Statistical analysis: Ryan Kerrigan’s impact and other notes from Cardinals-Redskins


— It’s hard not to notice rookie linebacker Ryan Kerrigan’s immediate impact. In two games he’s caused two turnovers, one for a game-changing touchdown. But he’s not just getting lucky in high-leverage situations. He’s been consistently making plays. He leads the Redskins’ defense in ‘Success Count’ (SC) —the number of plays that result in a statistical setback for the offense. SC tallies not only interceptions and fumble recoveries and sacks, but all tackles and assists, passes defended, quarterback hits, and everything else that decreases the offense’s net scoring potential. The addition of Kerrigan is one reason the defense leads the league in Run Success Rate at 40 percent.

— Quarterback Rex Grossman had another positive game despite two early interceptions with a net +0.29 WPA and +4.6 EPA, due primarily to his 4th down touchdown pass to Santana Moss on the game-winning field goal drive. On the downside, Grossman was poor on 3rd downs, which included both interceptions. Here’s his EPA on downs 1 through 3 for this season: 3.8, 4.7, -8.8. Including his games last season, his EPA by down is: 15.4, 10.4, -24.9. When defenses know a pass is coming, Grossman is easy prey. The Redskins should be mixing in a heavy dose of passing on 1st and 2nd down, when play action can be effective and pass rushers need to read run.

— It’s notable that the Redskins’ offense was able to accumulate 28 first downs with only six conversions on 3rd down. That’s instructive. The best way to avoid a stop on 3rd down is to never get there. Convert on 1st and 2nd down. Easier said than done, I realize, but long gone are the days when offenses should be nibbling with 3-yard gains on 1st and 2nd down to set up a “manageable” 3rd down.

— It was a no-brainer to attempt the two-point conversion late in the game, down 21-19. Grossman’s pass attempt to Moss was unsuccessful, as are most pass attempts in that situation. League-wide, teams pass too often on two-point conversion attempts. Overall, the league average success rate is 46 percent, but on straight-up run plays (non-scrambles or fake kicks), it’s 62 percent. And teams only ran 26 percent of the time over the past 10 seasons. Game theory dictates teams should be running significantly more often. Specifically, the math says that overall success rate will be optimized where the respective payoffs of running and passing equalize. Usually, these kinds of calculations are messy and complex in football. For example, how do you measure the increased risk of turnover in passes compared to runs? Or how do you measure the relative certainty of at least a small gain of a run? (This is where stats like WPA and EPA are especially useful.) But in the case of two-point conversion attempts, the payoffs are simple and clear: either you succeed or not.

 — This is shaping up as Fred Davis’s break-out year. So far, Davis leads all tight ends in WPA and EPA. He’s third in the league with 14.7 Yards Per Target and an 85 percent catch rate.

— With Dallas on the horizon, look for the Redskins to use their advantage in the running game. Dallas has been weak on both sides of the ball so far, notching a third-worst 29.2 percent Run SR on offense and allowing a 68 percent Run SR on defense. Keep your eye on Dallas’ one big bright spot on defense, second-year linebacker Sean Lee. He’s gobbling up tackles—21 total so far—for a Tackle Factor of 2.2, meaning he’s notching over twice the share of team tackles you’d expect for a player at his position. He leads Dallas with a SC of 15, two-and-a-half times his next closest teammate.

 A final note: You can find a glossary of terms and stats we use at Advanced NFL Stats here.

By Brian Burke  |  10:14 AM ET, 09/21/2011

 
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