Deep Stats: Opportunities and Challenges for the 2019 Penn State Defense

By Craig Fritz on August 22, 2019 at 8:00 am
Penn State Senior Defensive Tackle Robert Windsor
Matthew O'Haren-USA TODAY Sports
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Just like last year when I reviewed the improvements and failings of Brent Pry's unit, there is a reason for fan and team optimism heading into a new season. Things are pretty steady in State College. In Pry's four years leading the defense, his side of the ball has ranked 15th, 14th, 12th, and 11th nationally in S&P+. This is Penn State's full 2018 statistical profile (opens Google Sheet).

If you've never heard of S&P+ before, it's an advanced statistics system developed by Bill Connelly of ESPN (formerly SBNation). Here's some introductory reading. Basically, Bill's formulas measure how successful a team is offensively or defensively in specific situations on the field. Notably for 2018, Bill tweaked his formulas and added "Bill Walsh stats" along with some other changes.

One thing you'll note, compared to the 2019 offense's challenges and opportunities, there is much less fluctuation with the defense. That means basically most of the statistical categories stayed pretty much the same, so this will be a shorter article. Also, I'm sorry it took so long to get this one out! We had a kid and bought a house, so you know, L I F E.

challenges

This section is all about the tough task of making the good even better. These are spots where the 2018 Nittany Lions thrived over 2017. As you can see below, the Lions got even more sack-happy in 2018.

category 2017 2018 difference
adj. sack rate 45 7 38
standard down sack rate 69 6 63
passing down sack rate 33 18 15

That...that's every category with at least a 15-spot improvement. Call 2018 the year of the Wild Dogs if you like. They had an eye-popping 47 sacks, which led the nation in a per-game basis. Adjusted Sack Rate is exactly what it sounds like, a sack rate adjusted for opponent (for example, sacks against Ohio State are more important than sacks against Pitt). Standard Down Sack Rate, oh wow! That's quite an impressive jump. This means the Lions were able to generate a ton more sacks on regular down and distance plays when the playcall could easily be a run or pass. Passing Down Sack Rate is also exactly like it sounds. These are sacks in clear passing situations. So really, this is good stuff and the type of chaos DL coach Sean Spencer is looking for.

Here are a couple other measures of very impressive defensive performance that I wanted to call out. Not necessarily an improvement year-over-year, but an idea of what Pry's group is really good at.

  • Stopping big plays - Penn State was 3rd in Big Play Rate (20+ yards), 11th in defending Marginal Explosiveness, 5th nationally in Passing Marginal Explosiveness, and 2nd in Passing Down Marginal Explosiveness. All of these mean they kept the action in front of them, especially on obvious passing situations.
  • Making big plays - Overall, the Lions Havoc Rate jumped from 11th to 8th. Havoc plays are made at or behind the line of scrimmage. The defensive line was 5th in the nation in this measure.

opportunities

This is the less fun portion of our review. These are areas were Penn State was not as good as 2017 by at least 15 spots nationally. Improvement here will equal good things for the 2019 defense. What you'll note is that Pry's unit generally struggled defending the run, for which there are a lot of reasons, but it's concerning considering the conference they play in.

category 2017 2018 difference
field position 6 32 -26
rushing s&p+ 18 43 -25
opportunity rate 20 84 -64
Standard down s&p+ 19 36 -17
db havoc rate 8 22 -16
pd to inc 27 56 -29
  • So right out of the gate, we see the drop in Field Position. For a defense, this is a measure of where the team's offense started their drives. It makes sense if you are limiting the yards opponents get (i.e. three-and-out), it sets up your offense at a better spot on the field. After being lights-out at this in 2017, it slipped a bit.
  • Next we see where the most improvement could be made. Penn State was not great at defending the run, especially when the offense stalled and left the defense on the field for long, tortuous stretches. An improved linebacking and safety corps should help here.
  • Sticking in the run game, Opportunity Rate is the percent of rushing plays where the offensive line "does its job" by generating at least five yards for the rusher. So as a defensive metric, it shows how often or not the defense allowed those yards. We find a precipitous drop to well below average. Too frequently teams were able to get necessary yardage on the ground.
  • Think of Standard Downs as "staying on schedule." On first down, you want to get four yards or more. The same on second down, etc. This rating means the 2019 defense has a chance to throw a wrench into opponent drives at a higher rate than last year's group.
  • The defensive back Havoc Rate is still REALLY good, but it did fall from elite in 2017 (Marcus Allen, hello) to simply good in 2018. Havoc plays are tackles for loss, forced fumbles, and defended passes. 
  • Next, we come to PD to INC, which is a measure of aggressiveness that shows the percentage of an opponent's incomplete passes that you broke up or intercepted. It's no surprise that losing three NFL draft picks out of the secondary led to a bit of a drop here. Definitely something to watch for a rebound.

Finally, I want to harp on a statistic that I think really hammered after 2017 which didn't improve much in 2018. That statistic is linebacker havoc. In 2015 with Jason Cabinda, Brandon Bell, and Troy Reeder, the unit ranked 49th in havoc. Not great, not terrible. 2016 with Cabinda, Bell, and Manny Bowen, the number jumped to 29th (Imagine the Rose Bowl with Bowen not suspended and Bell not injured). Losing Bell for Koa Farmer in 2017 led to a drop all the way down to 92 in 2017, and the group wallowed there in 2018 at 88th following the departures of Cabinda and Bowen. To be clear, I thought this would be a rough area for Penn State last year. No where else is there such a clear need for improvement for the Nittany Lion defense than game-changing plays out of the LB unit. Now that depth is restocked and talent abounds, will 2019 be the year the biggest plays on defense come from LBU? 

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