Deep Stats Review: Defense Part 2

By Craig Fritz on June 27, 2018 at 5:00 pm
Penn State Cornerback John Reid

© Matthew O'Haren-USA TODAY Sports

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Despite leading a statistically elite defense for the second consecutive year according to S&P+, there were a couple (2) notable occasions in huge games where fourth-quarter defensive collapses contributed to brutal losses. Those games showed that the Nittany Lions still have work to do to build depth and secure across the board talent to reach the College Football Playoff. Today we're looking at the biggest year-over-year declines for Pry's squad (decrease of more than 15 spots nationally). To calm your nerves a bit, the declines are not numerous, but rather just a few big drops.

For those reading for the first time, S&P+ is an advanced statistical system designed by Bill Connelly of Football Study Hall and SBNation. We already went through the biggest offensive improvements and declines, and defensive improvements by Penn State last year. This handy glossary will help us decipher the inner workings of Bill C.'s system.

rushing 2016 rank 2017 rank difference
adjusted line yards 21 45 -24
power success rate 40 90 -50
  • Adjusted Line Yards (long explainer) attempts to make sense of who gets credit for success on run-only plays. Generally, the offensive line gets blame for losses, and runs that generate less than 5 yards. For the defense, this rating system measures the entire front seven, not just the defensive line. So a fall from good to mediocre in this statistic shows that the front seven wasn't as stout against that middle ground rushing game. They limited big plays, but also didn't make a ton of big plays of their own, which is shown in an 11 spot drop in Stuff Rate. I didn't include it in the chart because it's not 15 or more spots, but Stuff Rate is tackles of a runner at or behind the line of scrimmage.
  • Here again is a grit-yard statistic. Power Success Rate is the percentage of runs on third/fourth down, 2 yards or less to go, that achieved a first down or touchdown. It also includes runs on first-and-goal or second-and-goal from the 2-yard line or closer. So to be blunt, this is bad and has to be fixed. 
standard downs 2016 rank 2017 rank difference
standard down sack rate 54 69 -15
  • Standard Downs are first downs, second-and-7 or fewer, third/fourth-and-4 or fewer. These are the downs in which the offense could conceivably either run or pass and therefore has an overall advantage over the defense. Penn State fell off to a not-so-nice mark in 2017 at getting to the quarterback on normal down-and-distance situations.
passing downs 2016 rank 2017 rank difference
Pass down line yards/carry 30 60 -30
  • Here again is a middle-of-the-road rushing statistic that proved an area difficult to defend for the Nittany Lions. On obvious passing downs, the defense allowed opposing offensive lines to "do their job" and create at least 5 yards of rushing for their back much more often. I'm not sure there's a ton to gain from this one, however. If a team is way behind the chains (third/fourth-down and 10+ yards), and they run a draw for 7 yards, no one cares, but it drops this ranking for your team.
situational 2016 rank 2017 rank difference
4th quarter s&P+ 8 106 -98
  • WHAT? Is this an alternate universe? Remember our post on defensive improvements? Penn State got better in every quarter on defense last year (1st: +40, 2nd: +36, 3rd: +7), and then this complete and utter turd in the 4th quarter. 
  • Ok, deep breath. There are a bunch of things at play here. Having huge leads and playing depth late significantly contributes to this statistic (Nebraska scored 20, Northwestern got their only tuddy of the day). But also not having enough talented depth to make sure starters are fresh at the end of the game is legitimately a factor. Ohio State scored 19 in the fourth, Michigan State got 6 unanswered to win, Iowa got 12 of its 19 points in the last quarter requiring a heart-stopping comeback. You could extend this back to the Rose Bowl as well, when USC scored 17 in the 4th to win. There may be other factors, but regardless, Pry needs to figure out how to survive late onslaughts.
havoc 2016 rank 2017 rank difference
lb havoc rate 29 92 -63
  • Yeesh. Remember Havoc is the percentage of plays in which a defense either recorded a tackle for loss, forced a fumble, or defensed a pass. Brandon Bell was dearly missed, and the 2017 LB unit was a shadow of the linebacker standard that Penn State fans have come to embrace with regards to game-changing plays. Someone or someones will need to step up in 2018 to fix this black mark.

This is the final post in a series looking at the year-over-year improvements or declines in performance across the Nittany Lion offense and defense. I hope you enjoyed reading as much as I enjoyed compiling this series. [Part 1 - Offensive Improvement] [Part 2 - Offensive Decline] [Part 3 - Defensive Improvement]

Hit up the comments to discuss the ins-and-outs of Penn State's S&P+ and where you think we can expect defensive improvement in 2018!

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