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2014 Defensive Pass Identity Data

Yesterday, we looked at offensive Pass Identity grades. Today, we are going to use the same process to analyze the data for defenses.  Yesterday’s post is required reading to understand how Pass Identity grades are calculated, but here’s one update.  While we can use the same numbers for Game Script (including the 3.27 number for standard deviation and 0 for average), that’s not the case for defensive Pass Ratio. There, while the average is roughly the same at 58.29%, the standard deviation is much smaller at 2.84% (it was 4.66% for the offenses).

Let’s use the Lions as an example.  Detroit had an average Game Script of +0.4 last year, meaning the Lions were leading by, on average, 0.4 points during every second of every game.  That was 0.11 standard deviations above average.

The Lions saw a pass on 64.43% of all defensive plays last year, with a pass defined as a pass attempt or sack, and a play as a pass attempt, sack, or running play.1 That means Detroit was 2.16 standard deviations above average when it comes to facing passes — i.e., teams passed very frequently against Detroit.

To calculate the team’s Defensive Pass Identity, we subtract the number of standard deviations above average the team was in Game Script (here, that means subtracting +0.11) from the number of standard deviations above average the team was in Pass Ratio (+2.16).  We then take that result (+2.05), multiply it by 15, and add it to 100 to create an index.  This means the Lions had a Defensive Pass Identity of 130.8, the highest in the NFL in 2014.

RkTeamGame ScriptStDev GSPass RatioStDev PRPass Identity
  • So what does this mean in English? Well, the presence of players like Ndamukong Suh, C.J. Mosley, and Nick Fairley, combined with a secondary that started aging journeymen James Ihedigbo and Rashean Mathis, incentivized teams to be pass-happy against the Lions. Detroit was good against the pass, but outstanding against the run, so it makes sense seeing them high in these ranking. The Lions also faced the most pass-happy game of the year: on Thanksgiving, the Bears passed 51 times and ran just 8 (including one kneel) despite a Game Script of just -3.7.
  • Seeing the Jets second on the list won’t surprise folks who were regular readers of the Game Scripts articles. The Patriots passed on 72% of all pass plays in a game where New England had a Game Script of +2.9; the Bears passed on two thirds of all plays in a game where they had a Game Script of +9.1. The Chiefs and Bills both passed over 50% of the time in games where they had double digit Game Scripts. The Jets ranked in the top quarter of the league in yards per carry allowed and the bottom quarter of the league in ANY/A allowed. More obviously, with a front line of Sheldon Richardson, Damon Harrison and Muhammad Wilkerson and a secondary of replacement-level players, the only surprise is that New York didn’t rank first. And in one of the most run-heavy games against the Jets, there’s little reason to understand why Minnesota was so run-heavy.
  • While writing this article, it caught me by surprise that in 2014, Denver was a more attractive opponent for fantasy quarterbacks than teams like Tennessee or Oakland. After all, the Broncos had a top-three pass defense in the NFL in 2014. But teams passed more, and ran less, against Denver than versus any other defense in the NFL. Perhaps call it the delayed Peyton Manning effect: for years,2 it seemed like coaches tried to beat Manning by keeping him off the field and calling a lot of running plays. Seeing that strategy fail, it appears offenses have shifted to doing everything they can just to keep up on the scoreboard.
  • On the other side, the Packers really stand out, too. Remarkably so. Teams weren’t very interested in throwing on Green Bay last year, starting with this crazy game against the Bears. And Chicago didn’t throw very often in the rematch against Green Bay, either. Perhaps teams were trying to keep Rodgers off the field, or perhaps teams simply gave up in a sense, and chose not to throw as often as you’d expect while trailing against the Packers. But it’s pretty unusual for a team to lead the league in points scored and also rank in the top ten in rushing attempts faced (i.e., face a lot of rushes). The last team to do that? The 1990 Buffalo Bills. Green Bay was good (but not great) against the pass last year, and the team did have some struggles in run defense. But the difference between how teams attacked the Broncos vs. the Packers is pretty startling, given that those teams had the two best Game Scripts averages in 2014.

What stands out to you?

  1. Unlike yesterday, kneels and spikes were not excluded, since I only have that on the season level in my database for offenses. []
  2. For example, see the 2006 Colts. []
  • Anders

    How on earth didnt teams pass more against the Eagles consider how good their run defense was compared to the horrible pass defense?

    • I really don’t know. It’s funny, the Eagles ranked 31st in passing yards allowed. 31st! Yet somehow, I’m saying teams didn’t throw enough on them. That’s a function of a lot of things:

      1) Philly played at a very fast pace. The offense ran the most plays in the NFL, and the defense faced the 2nd most plays in the NFL.

      2) The Eagles had a pretty good Game Script, so you’d expect a good number of passes against them.

      3) While the Eagles ranked 31st in passing yards allowed, they were “only” 27th in pass attempts faced. And they were 28th in rush attempts faced. And, as those ranks imply, the Eagles were actually below average in pass ratio faced.

      So add in a strong Game Script, and it kind of makes sense. It still may feel weird, tho.

  • Adam

    That Packers/Broncos dichotomy is quite bizarre. I think you’re right that teams simply gave up against the Packers and wanted the game to end as quickly as possible. They had more first half blowouts than any team since probably the 07 Patriots. Having watched every Broncos game, I noticed that Del Rio’s defense played a very soft prevent style while leading in the 4th quarter, so teams were incentivized to keep passing, even if for no other reason than stat padding.

    • Yeah, that could be part of it.