The cliche about Northwestern's defense is they "don't know how to step on throats" or "finish the game" or have a habit of "letting teams stick around." I'm sure we've all heard these things and brought them up anecdotally, but I don't think anyone's ever done the math on these things. Well I got curious to see if this cliche was actually true, so I did some number crunching.
It seemed to me that NU plays two different ways under two different situations (at least this year). When they're playing in a close game, one where they're either losing or up by less than a TD, they've been pretty close to lights out. However when you spot them a lead of more than two scores the story gets a little different. I've taken every defensive series played by Northwestern this year against non-FCS competition and culled out the interesting numbers, and then categorized them based on whether that drive took place when NU was playing with a "comfortable lead" (margin >=9 or when they were in a "close game" (margin <9). Once completed, I've calculated the average yards per play in each category of drives, the average score allowed per drive, and the average yards allowed per drive. There's more information I could gather from this (drive times to account for pace of play, things like that) but I was less interested in coming up with a "why" at the time so much as coming up with a "Is this really something that exists."
Facts and figures after the
jump invisible line that no one ever sees anymore! So right now!
Boston College (Green because Word doesn't have a pre-formatted gold design)
So these are a lot of numbers. Looking solely at the yards per drive, it becomes very obvious that NU's defense had trouble getting off the field when they were playing with a comfortable lead. The Indiana game is incredibly revealing in this regard. There were far more drives when playing with such a lead, and these drives yielded almost 30 more yards per drive than when playing a tight game. Similarly, NU didn't give up a single point when playing close, but rather all when playing from way ahead. This is also true in the BC and Cuse games, even though they didn't surrender any points when playing with a large lead against BC; the yards per drive are still double from close to comfortable. For Syracuse it's a perfect storm; when playing with a large lead the measurable statistics got markedly worse.
The Vanderbilt game is a little bit of an outlier as Northwestern didn't have a comfortable lead until the Vandy's last drive. On that drive, Vandy was in desperation mode and heaving the ball downfield for incompletions. That said, the defensive numbers when playing in a close game are in line with the other close game numbers (less than 1yd/play, about 1pt/drive).
So what can we learn from this? Well with small sample sizes statistics can tell you anything. These statistics here are telling me that Northwestern is worse when playing with a comfortable lead. As I said, I didn't go into the why but I suspect that the reason is twofold: First, teams start passing more and playing with a "win now" mentality. These drives tend to focus more on our weak secondary than a more balanced run/pass gameplan would normally. Also, I suspect these drives tend to be quicker, with the opponent trying to take less time off the clock. It takes time to build up a comfortable lead, so there's usually less time remaining which yields a hurry-up offense. There may be some defensive scheme adjustments that account for this, but my expectation of a prevent defense would be to prevent long plays and give up the short routes, and I haven't noticed noticeably more short passes into either the flat or the sideline during NU's games. It seems to stem entirely from teams throwing the ball farther more frequently. I have no justification whatsoever for this as I didn't feel like breaking down the play by play for each drive (maybe someone can crunch those numbers), but I think what I've discovered is telling. NU needs to get better when playing with a lead (er... duh?)