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Northwestern by the numbers: pass defense

“Northwestern by the Numbers” is our humble attempt to break down some of the Wildcats’ more notable statistics (team or player-related) from last season, and try to predict if and/or how they will change this upcoming season. The second part of our analysis won’t include as many statistics, simply because projecting improved or depressed performance is less scientific, and involves more observation and guess work, than reviewing old data. (A note: we will be using advanced stats from FootballOutsiders in our explanations. If you’re unfamiliar with any of these numbers, check out the FO stats info page for explanations of the various measures they use to quantify performance.) 

Our hope is to offer a unique numerical perspective to the team you watch and read about every week. And hey, next time you’re locked in a Wildcats-involved team or player debate with a friend, or are particularly keen on impressing your boss at the office holiday party with some wonky football insight, or simply strive to sound smarter when discussing NU football, it never hurts to have some statistical ammo at the ready.

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Stat: 250.5 pass yards allowed per game, good for last in the Big Ten.

Why it happened

On a comprehensive scale, Northwestern’s defense graded out fairly well in 2012. After finishing 101st in FO’s F + ratings in 2012, the Wildcats jumped up to 46th last season. They also ranked 5th in the Big Ten in average points allowed (22.5), down more than five points from 2012’s mark (27.7). But the problem of stopping the pass continued to haunt the Wildcats through their 10-win season, and the above metric – while crude on its face – underlines that weakness.

On standard downs – defined by FO as anything that doesn’t fall under the following: second down with 8 or more yards to go; third or fourth down with five or more yards to go – the Wildcats fared capably against the run and pass, finishing 46th in the country in defensive S&P + (a measure of situational “success”). Passing downs were a different story entirely. Not only was Northwestern unable to consistently stop the pass (they ranked 95th in defensive S&P +), opponents barely bothered trying to run the ball in these situations, rightfully convinced they could advance drives through the air. The Wildcats were passed on 73.8 percent of the time on passing downs, almost eight percent more than the national average. Eliminating, for a moment, the passing downs distinction, opponents attempted 289 passes against NU’s defense last season, tops in the Big Ten.

This, as you can probably imagine, is something of a problem, particularly because the Wildcats weren’t terrible against the pass when measured in both passing and standard down situations; their 102.1 S&P rating against the pass ranked 53rd nationally. All of which paints a picture of a defense that was solid against the run and the pass on non-passing downs, but unable to stop opponents through the air on crucial second and long and third-down situations, the bane of any defense’s drive-ending desires.

The Wildcats were able to force opponents into onerous down-and-distance situations, but weren't able to force punts and get off the field nearly as often as they might have liked. Naturally, this is a frustrating phenomenon, one NU struggled to combat effectively. The accumulating effect of numerous third-down conversions and extended drives has the potential to enervate any defense, let alone the demoralizing effect of shutting down an opponent's offense on first and (some) second downs and, in a matter of seconds, watching the same opponent pick up a new set of downs after converting a long pass play.

Why it could change 

Pass defenses can’t be fixed overnight. In college football, they evolve in fits and waves, infused with new recruiting talent, weakened by graduation and NFL-related departures. In 2013, the Wildcats pass D will attempt to replace three major contributors from last season: Demetrius Dugar, Quinn Evans and Jared Carpenter. All of these players contributed at various points of the season, with different levels of success, and even if they made plenty of mistakes along the way, their presences will be missed (Carpenter in particular).

The two best starters from last season’s pass defense (cornerback Nick VanHoose and safety Ibraheim Campbell) return, which should ensure the Wildcats have a solid foundation to build around in the back end of their defense. Campbell closed last season playing at an all-conference level, while VanHoose, provided he stays healthy, has developed into one of the league’s better cover corners. Both players should play as well or better than last season. Their performance alone gives Northwestern the individual talent and playmaking ability to improve upon 2012’s regrettable pass-defending efforts.

Controlling for VanHoose and Campbell’s reliably stout performance – In other words: let’s just assume, for the sake of argument, both guys will remain two of the league’s better DB’s this season – the composition of the rest of the pass defense will help determine if the pass defense can improve, and, if so, to what numerically-measurable degree. Traveon Henry ran with the first team lineup at safety throughout spring practice, and early reports from training camp strongly recommend Daniel Jones’ claim to the other starting cornerback spot. A number of other competitors – including Jarrell Williams, Jordan Perkins, C.J. Bryant, Dwight White and any of four true freshmen – are likewise expected to challenge for the starting position.

The group, as a whole, is young and inexperienced, but probably more talented than the various quartets Northwestern trotted out in 2012. It’s impossible to say whether that will translate to an “improved” pass defense. There are too many unknown variables –VanHoose’s borderline injury prone history, Campbell’s possible regression or corresponding improvement, the variability of Jones’ week-to-week performance, the unfamiliarity of a true freshman potentially trying to lock down some of the Big Ten’s best receivers – to consider. The Wildcats have fielded some of the worst secondaries (statistically) in the Big Ten in recent seasons, and 2013, while promising for the youth and athleticism the secondary will feature, probably won’t yield a sea change of newfound pass-defending quality. Marginal improvement is my modest projection. If everyone stays healthy, and the youngsters take to their new positions while avoiding some or most of the early struggles first-year defenders often endure, significant upward revision is possible.