With the news coming out that Manny will serve as the playcaller for the defense, returning to the de facto DC position, I wanted to dive deeper to establish whether Coach Diaz was a top-shelf DC or not.
Methodology
It started with a Twitter debate, where fans online perceived Coach Diaz as either an average DC, or even a poor one. From there, I asked for fans to identify the top-5 DC’s currently in college and received a list of various names. I settled on these names:
- Brett Venables- Clemson
- Marcus Freeman- Cincinnati (now Notre Dame)
- Dave Aranda- LSU (now HC at Baylor)
- Jim Leonhard- Wisconsin
- Jon Heacock- Iowa State
- Blake Baker- Miami
There are other worthy candidates, but this list seemed like a representative start of identifying how standout DC’s perform in their roles.
I am using a
sample size of three years for each of them, except for Baker, as I am using him for a control to show how Miami fared under Baker as opposed to Manny Diaz.
The metric I am using is
Yards Per Play. I chose Yards Per Play (YPP) because it is simple to calculate, readily available, and is a good catch-all for how a defense fares against an opposing offense overall.
To gauge how a team fared against peers, I am removing teams that are not of like-quality. I.E. a Power-5 team, I am removing all non-Power-5 teams from their results. For Cincinnati, I am removing lower tier FBS teams and all FCS teams. This helps to stabilize the talent of the teams and removes a defense beating up on the Missouri State’s of the world.
From here, I calculated the “
Win Percentage” that a DC against opposing offenses. A win is holding the offense under their standard average against other peer-like teams, a loss is allowing them to outperform their YPP against that DC’s defense.
Additionally, I wanted to calculate the “
Difference” between what each DC allowed on YPP and what those opponents averaged against other peer opponents.
I also calculated the standard deviations of the opponents’ offensive performance and tabulated the number of times each DC held their opponents one standard deviation under their average and two standard deviations. I calculated how often the DC allowed their opponent to outperform their average by one and two standard deviations as well.
Results
By looking at performances against peer institutions and then then weighing it against their offensive performance against other peer opponents I believe you are getting at the actual contributions of each DC and can accurately gauge the quality of coach. The results pass the “smell test” as well, with Venables being far and away the best and Blake Baker being far and away the worst.
Here are the results for % of games holding opponents under their norms (Win Percentage):
View attachment 143007
Coach Diaz fares very well here, finishing second among the group of DC’s with a win percentage of 77.4%. Venables leads the pack, as he does in every category, by holding an opponent under their norms an astonishing 86.5% of the time. Keep in mind, this is against peer institutions, so no Bethune Cookman’s propping up that number for Venables (or anyone).
Surprisingly, Blake Baker did not come in last here, as Jim Leonhard and Jon Heacock both finished lower than his 68.4% showing.
Here are the results for Yards Per Play (YPP):
View attachment 143008
Again, Venables leads the way, with Coach Diaz coming in second. Marcus Freeman is the third DC to hold opponents to under 5 YPP, but keep in mind he is doing that at Cincinnati, with a decided talent advantage against even some conference foes. Clemson may have a talent advantage over their opponents, but the revenue from the ACC to each team at least allows them to be competitive in resources. Some teams in the AAC have a wide budget gap between themselves and Cincinnati.
Blake Baker comes in last in this metric, not surprisingly. That is a gap of .58 yards per play allowed between Baker and Diaz, which is cavernous.
Finally, here are the results for how each DC fared at holding their opponents below their norms (Difference):
View attachment 143009
Venables comes in at a ludicrous -1.17 YPP against peer institutions and their offensive averages. Marcus Freeman is second, but Manny comes in third at -0.84 YPP.
Blake Baker does not finish in last place in this metric, surprisingly, Jim Leonhard does. Leonhard appears to be a bit overrated by fans currently.
Overall:
For those of you who just skip to the end, suffice to say, Coach Diaz comes in second amongst this group of DC’s over a three-year sample. Over this time, keep in mind that Coach Diaz only had Gerald Willis for one season and had three true freshmen LB’s to scheme around. Then he introduced the Striker into his defense in this sampling as well. Venables, Aranda, Leonhard, Heacock are considered among the best names in the game, so Coach Diaz is definitely an excellent DC, who will be a massive upgrade over Blake Baker.
In looking at the performances of Coach Diaz, a few things stand out:
- Coach Diaz will consistently hold an offense under their norms, but will generally not dominate an offense (over one standard deviation under their norms), as he did this in only 29% of games. Venables did this an absurd 57% of the time. Coach Diaz has only held an offense two standard deviations under their norm once (Against Virginia in 2018), while Venables has done that six times over the last three years.
- Coach Diaz’s defenses are remarkably consistent in their ability to scheme negative plays against an offense and hold their overall performance down.
I went into this exercise expecting to find Coach Diaz was outside of that elite tier of DC’s and would be solidly in the “good” tier, but the data confirms that Coach Diaz profiles in the 90th percentile of DC’s in the country and will put up a performance far better than we have seen over the past two seasons.
