I thought that myself when I read that article that talked about a Data Scientist(tm)
butt (not jake butt)
Last week we took a look at run defenses, and concluded that Rutgers isn’t the steaming pile of hilarity we’re all expecting. This week, we’re taking the same look at pass defenses. Spoiler alert: Rutgers IS the steaming pile of hilarity we’re all expecting. If not steamier and… uh… more pile-like. The question at hand is as follows: who will have the best pass defense in the Big Ten in 2014?
If you’ve forgotten, we’re just taking a simple two-step process: we look at how good teams were last year at a thing, and we look at attrition among the folks responsible for the thing. Our key assumptions are as follows:
- Experience is good and, all other things being equal, makes things better than they were.
Were they good last year?
Again, this is the easier piece.
Yards per attempt allowed, adjusted for sacks: YPA is generally considered the statistical gold standard for overall goodness of passing games, so it is a pretty useful stat for demonstrating pass defense (It is almost certainly superior to cumulative stats. Yards per game can be misleading based on differing numbers of attempts; Purdue was middle of the pack in terms of YPG allowed, but that’s only because they faced fewer passes because their run defense was so ungodly atrocious, and they were usually behind, so offenses didn’t really feel the need to throw the ball).
We've adjusted for sacks, counting a sack as a pass attempt, which makes sense because if you drop back five times, and complete one pass for 10 yards while getting sacked four times, your yards per attempt should really reflect the fact that attempting to pass went poorly most of the time.
|Team||YPA - sack adj.|
Passing S&P+ Defense: Click the link for a thorough explanation, but it is an advanced statistical model analyzing what defenses allow on a given play against what you would expect. Advantages are that it takes opponent strength into account, it factors in sacks, and it filters out garbage time. Numbers are national rankings.
20+ yard passing plays per game: Completions happen. A team will often gladly offer an opponent a 10 yard completion on 3rd and 17. But 20+ yard completions are a strong indication of a pass defense prone to breakdowns, and one that cannot do the thing it is trying to do.
|Team||20+ yard passes/game|
Sacks per game: Sacks can be either a cause of good pass defense or a symptom of good pass defense. A quality pass rush will lead to better defensive results when the opponent tries to pass the ball (see: Nebraska and Ohio State), and solid coverage will lead to more chances for the pass rush to get home with “coverage sacks” (see: Michigan State). It’s hard to separate the two causal possibilities, but for our purposes we don’t need to. They’re both good.
Putting it together
Here is how the teams shake out in rough order of how they fared in the above categories, with emphasis on the first two categories.
Like last week the teams generally break out into four tiers:
MSU – MSU.
- Again, they get their own tier because obviously.
Pretty Good – Iowa, Wisconsin.
- Great YPA numbers, minimized big plays, didn’t get home much on pass rush.
Meh - Penn State, Maryland, Ohio State, Michigan, Nebraska, Northwestern, Minnesota.
- The great undifferentiated mass of mediocre pass defenses. All allowed between 5.87 and 6.30 YPA (other than Maryland, who played a weaker schedule last year). All but Northwestern had S&P+ pass rankings between 41st and 64th.
Butt (NJB) – Purdue, Rutgers, Indiana, Illinois.
- If you’re curious, all four of these teams performed comparably with, and perhaps even worse than, Michigan’s 2010 pass defense.
[AFTER THE JUMP: Attrition tolls for thee. If thee be Ohio State or Nebraska]
After securing my copy of the Akron game, which somehow didn't instantaneously melt my hard drive, I solicited GIF requests on Twitter. A sampling of your responses:
There were also requests for kittens, corgis, Henrik Zetterberg, and a Men In Black-style memory erase. This quickly devolved into people sending me GIFs of adorable animals. I may have requested this, too.
Worst win ever? Worst win ever.
[After THE JUMP: actual football GIFs. Well, for the most part.]