Yesterday, Tex talked a lot about expectations. It was good and well worth the read if you haven’t already done so. I’d also been on something of an “expectations” binge having previously laid down some expectations about Will Fuller, Greg Bryant, Justin Yoon, and Max Redfield. Quite frankly, I started to get worried that we were going to start sending readers to the doctor with all of this bottled up excitement, so I decided to switch gears for a week. The good news is we’ve hit July. The bad news is it’s only July. Still plenty of time to discuss what our college application hopes and dreams for the future are, but today is not that day.
Instead, today seems like a good moment to pause and consider an aspect of last year’s defense that went wrong – the team’s inability to sack the opposing quarterback. If we’re being honest, it’s now been a problem in back to back years after the defense was fairly successful during the National Title Game run in 2012. It seems like an eternity ago that Stephon Tuitt, Ishaq Williams, and Aaron Lynch committed in one class to Notre Dame. At least part of the issue is that it seems like virtually no names have emerged along the defensive line since then.
That sentence is not intended to diminish the quality careers of players like Sheldon Day and Jarron Jones, but let’s be clear about something else: Those two combined for a total of 2 sacks last season. Romeo Okwara led the team with 4.0 sacks. Consider this: Utah’s Nate Orchard had 4.0 sacks just versus UCLA on October 4th. Tuitt’s 2012 season when he notched 12.5 was the last Irish player to reach double digits in sacks during a single season. At the present, it’s difficult to be optimistic that 2015 will put an end to the sack drought. The issue is if Notre Dame wants to take a leap forward, the sack rate’s got to improve. Significantly.
I’m burying the lede here, and perhaps it’s intentional given that my general position is simple and straightforward: sacks, and more specifically sack rate is a strong component indicator of defensive health. The last two years, Notre Dame just hasn’t stacked up. But, I wanted to provide some insight into just what sack rate can mean as an indicator of defensive health.
First, let me quickly define “sack rate.” While some analysts and sites like to focus on “sacks per game,” the issue I have with this statistic is it’s fundamentally context and opponent dependent. Notre Dame’s 2015 schedule includes match-ups with Navy, Georgia Tech, Boston College, and Pitt. Those 4 teams ranked 117 or lower (of 128 top tier teams) in pass play percentage. The opportunities to sack a quarterback, in terms of the sheer volume of passing snaps, is not likely to be high for the Irish defense next season.
What sack rate does is helps quantify how good a defense was at sacking the opposing quarterback when a passing play actually occurred. In a given season, the very best defenses will sack the opposing quarterback somewhere between 10-12% of pass drop backs. The very worst will do so in the 1-2% range.
Last season, Notre Dame finished 69th (putting them slightly below average) at 5.92%. 2013 was even worse when the Irish finished 85th nationally at 4.90%. This comes as no shock to all Notre Dame fans that quarterback pressure and sacks has been an area of serious concern for several years running now. I wanted to know whether sack pressure did in fact correlate to good defense. Yes, yes, I’m with all of you who are already yelling at your computer screen MOONS, OF COURSE IT DOES YOU IDIOT. That’s fine. There’s no need to yell. But saying “of course” and knowing the “of course” are two different things. Let’s consider the Top 20 and Bottom 10 teams by sack percentage last year:
Points Per Game Allowed: As a general rule, the twenty best at sack percentage were also among the best at suppressing opponent points. 60% of the top twenty (that’s 12 teams for the percentage disinclined) also found their way into the Top 35 teams in the country in fewest points allowed per game. Interestingly though, 2 of the 8 teams from the Top 20 not among the 35 best in points allowed was the number one team in sack percentage, Utah, and the number three team Louisiana-Monroe. The teams that were least successful at converting sack percentage to points per game allowed success came from the non-Power 5 conferences. Arizona State was the only Power 5 team with an elite sack percentage rate who did not finish in the Top 50 in points per game allowed.
Among the ten teams with the worst sack rate, there was one major outlier – Notre Dame’s bowl opponent LSU. LSU, shockingly enough, was just 119th nationally in sack percentage yet finished 6th nationally in points per game allowed. LSU’s pass defense overall was still spectacular which goes a long way to explaining this discrepancy. Of the other 9 cellar dwelling teams in sack percentage, the best points per game against rank belonged to known ball hog Navy…at 72nd nationally.
How did Notre Dame do at converting their 69th best sack percentage into opposing team points? ND finished 78th nationally in PPG allowed.
Completion Percentage Allowed: It occurred to me that perhaps sack percentage also served as a shorthand method of diving which teams were better at applying pressure to the quarterback and thus inducing a lower percentage of pass completions. Again, the answer came out that 60% of the sack percentage top 20 finished in the top 35 for lowest completion percentages allowed. More notably, it also included 6 of the top 11 at restricting completion percentage. The PAC-12 teams struggled the most at converting elite sack percentage into lower completion rates. Stanford, Utah, Arizona State, and Washington composed 4 of the 8 elite teams that failed to make the top 35 in completion percentage against. Stanford was the only one of those 4 to even crack the top 50.
In some respects, this makes sense given the extreme pass happy nature of the PAC-12 as currently assembled, although again, we’re considering the teams that were best at sacking QB’s on a per attempt basis. The issue for these teams seems to be if they didn’t get home, they weren’t applying pressure to limit the passing game otherwise. Stanford did an exceptional job at limiting yards on a per attempt basis finishing second in that regard (and thus suggesting that teams dealt with Stanford’s pressure by simply throwing the ball a shorter distance), but the other PAC-12 teams struggled in this regard as well.
The worst at applying pressure were also predictably terrible at curtailing completion percentage. Once we take out LSU who much like Stanford appeared to have teams adjusting to their style of defense by altering routes, the remaining 9 were truly abysmal. 6 of those 9 were in the bottom 10 for completion percentage allowed as well. It’s not surprising but should be startling just how strong the correlation is towards the bottom. If you don’t apply good, consistent pressure, teams will complete their passes against you.
Notre Dame suffered the fate of a team struggling to make it to the opposing QB finishing 86th in completion percentage allowed.
Third Down Conversions: Where sack percentage really showed was in third down conversion rate. 16 of the top 20 (80%) finished in the top 35 nationally for lowest third down conversion rate. 19 of the 20 (95%) finished in the top 40. Only Rice, once again a non-Power 5 team, did not convert an elite sack percentage into a top 40 third down defense. People love talking about the importance of getting off the field on the third down. Quite simply: there are few if any better indicators of third down defense than sack percentage.
LSU was the only team among the bottom 10 to crack the top 40 (33), but even LSU suffered by not applying the same pressure. For a team that finished 6th in scoring defense, 3rd in yards per pass attempt, 12th in completion percentage against, and did not have a terrible rush defense, a 33rd ranking, while still quite good, was harmed by the failure to get home.
The best rank any of the other bottom 9 could muster in third down conversion defense belonged to the Fighting Diaco’s of UCONN who finished 82nd.
Notre Dame, in line with everything else, finished 65th.
So What Does This Mean?
Well, for starters, that sacking the opposing QB remains probably the single most important skill for a defense to possess and the one that’s really been lacking from Notre Dame’s arsenal since 2012.
The other thing I think is worth considering is that sack percentage is a component statistic that you can watch early in the season to gauge the health of the defense. By the quarter mark or so, if the defense isn’t getting home for sacks, then regardless of what the scoring defense numbers might say to the contrary, there will be reason to worry.
The good new for ND and its fans is that sack percentage does not have a strong year over year carry over except at the very top and bottom. 12 of the top 20 in 2014 were in the top 35 in 2013, but several made huge leaps. Louisiana-Monroe went from 120th to 3rd. Wisconsin from 78th to 6th. Tennessee from 91st to 14th. At the other end of the spectrum, 6 of the worst 10 were ranked 104th or worst in 2013 as well. Only two (LSU and Eastern Michigan) saw a drop from the top 64 all the way to the bottom 10.
For Notre Dame sitting in the 60’s, I looked at all teams that had a sack percentage rank in the 60’s between 2010 and 2013 and saw how they did the next year. It was very much a crap shoot. 18 teams improved their ranking, 21 teams got worse, and 1 team had the exact same ranking the next season. A team was just as likely to rocket up the rankings by 30 slots (9 teams did this) as it was to drop by 30 or more slots (another 9 did this). Were I to graph out the results, it would look almost exactly like an inverted bell curve.
The point being, teams in the middle do not see a strong causation between one year’s results and the next. The optimists can take this as grounds for drastic improvement. The pessimists can take this to mean the exact opposite, and quite frankly, you’d all be right.
What’s not in debate: Sacks and sack rate are every bit as important as we thought they were. (cue Dennis Green clip here). I’ll talk about expectations of some more defensive players in the weeks to come with a particular eye towards their potential impact on this important improvement need for the Irish in 2015.
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