Analytics, Basic Stats, and Recent Historic Context: The ABC’s of Penn State Football – The Manny Diaz Hire, Part 1 – Immediate Improvements
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Introduction
Now that Penn State’s first spring practice is officially in the books, the bitter, lingering aftertaste of the way up then way down 2021 season has been chased by our first shot of hope. This year, a key ingredient mixed in the collective Kool-Aid we all seem to guzzle around mid-March is the hire of new defensive coordinator Manny Diaz – The Father of the Turnover Chain and the former DC and Head Coach of Miami. Manny Diaz comes to Penn State with an impressive pedigree as a defensive coordinator that includes various stops at places like Middle Tennessee (2006-2009), Mississippi State – twice (2010 and 2015), Texas (2011-2013), Louisiana Tech (2014), and Miami (2016-2018 as DC; 2019-2021 as Head Coach).
Diaz’s lengthy resume got us wondering, “How have Diaz’s Year 1 defenses compared to what the departed DC did the previous season?” Well, we found out.
Because our tracking only dates back to 2009, we’re gonna start our analysis during Diaz’s first of two pit stops at Mississippi State (to FTB’s loyal Blue Raider readership, sorry). As always, we’re going to look at everything – from basic stats to more advanced stats — to determine Diaz’s immediate impact on a defense.
Yardage
We’ll start with yards-per-game allowed. To clarify the graph you’ll stumble upon two paragraphs from now and throughout the rest of this story, each dot represents the performance in a statistical category, each number on the vertical, each year is at bottom of the x-axis, and each particular school is at the top of the x-axis. So, the left most dot represents the yards per game Mississippi State allowed in 2009 — 382. In Diaz’s first year at Mississippi State, 2010, the Bulldogs allowed 359 yards per game – a 23-yard improvement in one year.
In fact, creating stingier defenses upon arrival is a trend we saw throughout Diaz’s career, as his first-year defenses bettered the previous year’s defense in yards-per-game 4 of out of 5 times – Diaz’s 2011 debut at Texas being the lone exception. Diaz’s two most impressive defensive transformations occurred at Louisiana Tech in 2014 (46-yard improvement) and Miami in 2016 (74-yard improvement). From 2015 to 2016, the Hurricanes rose 36 spots in the yards-allowed-per-game FBS rankings (from 68th nationally to 32nd). From 2013 to 2014, the ..Lady Techsters? Hold on (googling)…the Bulldogs rose 66 spots (from 90th nationally to 24th).
There’s an explanation for why 2011 Texas didn’t best 2010 Texas: those 2010 Longhorns were 6th in yards allowed in FBS at 300 YPG. Plus, Diaz’s 2011 drop to 306 YPG still had Texas ranked 10th in all of the FBS. There was, however, a considerable drop in 2012 (403 YPG, 58th nationally). Conversely, we didn’t see the same drop at Miami. Instead, his 2nd and 3rd years as defensive coordinator were better than year 1 in YPG. Diaz’s big drop-offs at Miami came when he was the head coach.
In terms of yards-per-play allowed (YPP-A) we see virtually the same trend. Diaz showed immediate improvement or maintenance in every stop and several years of sustained performance at Miami. For context, an average defense allows 5.7 YPP and a top-10% defense allows <4.8 YPP. At Texas and Miami, Diaz had several defenses that were around the best 10% since 2009. His best unit in this category, the 2018 Miami team, is the 60th best since 2001 (that’s out of 1640 teams!). So that’s very good.
Scoring, Red Zone, and Explosivity
Switching gears to scoring. Let us start with points-per-game allowed (PPG). Similar story here as Coach Diaz tends to improve this metric during his first season as DC. In this category, an average FBS defense allows 28.2 PPG and, as you can see in the graph below, Coach Diaz’s defenses have rarely been worse than average in giving up points. In fact, only one year (2012 Texas) was he below average. Note that in this graph, I also added the first year post-Manny (orange) and it’s interesting to see that in some cases (Miss St-2nd stint and LA Tech) there was a marked decline immediately following Diaz’s departure. Texas post-Manny in 2014 showed a slight improvement versus 2013 but it continued a trend of improvement he had in 2013.
One final bit of context here: Since 2009, only 190 (out of 1640) college teams have allowed fewer than 20 PPG for a whole FBS season…and Diaz’s 2016 Miami team is one of them! That’s 89th %-tile overall during that time. Actually I lied…here’s a little bit more context: Penn State’s defense has allowed less than 20 points per game seven (7!) times since 2009 – 3 times under Brent Pry, 2 for Tom Bradley, 1 each for Bob Shoop and Ted Roof. So, with that established, if Penn State plays to what average Coach Diaz squad does — allowing a better-than-average 24 PPG – that will actually be somewhat of a letdown versus a typical Penn State team from the recent past.
Moving on to Red Zone scoring, we’ll explore what Diaz’s defenses allow in Red Zone points per attempt (RZPPA). As we covered in the defensive retrospective way back in January, the 2021 Penn State defense was lights out in this category — 3.4 RZPPA, which was 3rd in the country and 14th best overall since 2009. Only Coach Diaz’s two Mississippi State defenses held opponents to 4.0 RZPPA or less. Typically, his defenses end up closer to the 4.5-4.7 range. That’s not bad. Diaz’s 4.6 RZPPA average is still around the 70th %-tile since 2009. Therefore, even with the major departures from Penn State’s 2021 defense, we should expect Diaz’s first group in Happy Valley to finish good to very good in RPPZA.
What about scoring from outside of the Red Zone, though? The inclusion of ths new stat in this particular post marks the beginning of our new proxy for Explosivity. We’ll deep diver into PORZ (Points-Outside-Of-Red Zone) more next week with a standalone article on the stat but, for today, we are just looking at the average PPG given up by Diaz’s teams that came on plays from out of the Red Zone (technically this includes scores by opposing defenses, as well, so we’ll fix that in later iterations). The graph below shows the distributions and averages by year since 2009. You see that the FBS average is about 10 PORZ (Points-out-of-RZ) and the best teams are <4 (Yes, there is an artifact dot at zero in 2020. It was Arizona State and it’s real). Bad teams are >14 PORZ — translation, those squads allow a couple of TDs, on average, from outside of the 20-yard line each game.
Diaz’s teams, sans 2015 and 2021, have ranged between good (8.4 PORZ) and very good (anything less than about 6) in this category. Additionally, Diaz has improved a team’s PORZ from the previous season 3 of 5 times he’s taken over a defense.
Havoc
One of the hallmarks of Diaz’s teams is the creation of negative plays that put opposing offenses behind schedule. Havoc (sack, tackle-for-loss, interception, or fumble recovery) plays can be extremely disruptive, therefore it stands to reason that the best defenses generally generate a lot of Havoc plays per game (HPPG). On average, FBS defenses record 9.6 Havoc plays per game. The top 10% of defenses in overall effectiveness average 11.1 Havoc plays per game, and the top 10% (164 teams out of 1640 since 2009) of Havoc generators get 13 HPPG. Manny Diaz has orchestrated 5 teams that landed amongst those top-10% of Havoc generators since 2009. Diaz has NEVER finished a year below average in Havoc. See for yourself:
Looking more specifically at the tackles-for-loss and sacks that his defenses generate we see a similar story. An average team gets 8.2 TFL+Sack per game (leaving the balance of Havoc plays to turnovers). Coach Diaz has averaged 10.7 TFL+Sack. In 2018, his Miami team generated 13.3 TFL+Sack, which is the 4th best overall since 2009.
Overall Effectiveness
We finish with the Overall Effectiveness (OE) rating. This is a combination of a variety of factors and is the single number that we use to represent a defense’s dominance (or lack of dominance), as a whole. Lower the score, the better. A value of 30 OE is average, 22 OE is in the top 25%. When Manny Diaz arrived at Mississippi State in 2010, he took an average defense and immediately turned it into a top quintile unit. At Louisiana Tech, he improved an already good defense and at Texas he maintained a top-tier unit. When he arrived at Miami, he took an underperforming group and made them #elite instantly and maintained that performance for four straight years. He had had only one below average season as DC (2012 Texas) and immediately turned it around the following year. Hey, everyone is entitled to an off year, right?
To sum it all up, Manny Diaz isn’t going to come in and break the defense. He has a track record of maintaining great defenses and improving bad defenses. The 2021 Penn State defense was a historically good unit and we likely can’t (shouldn’t!) expect much improvement in scoring or yards allowed going into 2022. But, maintaining performance as close as possible to the 2021 team, with more Havoc generation, would set the defense up to do its part to win a Big Ten championship.
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