Photo by Eric Francis
Nebraska Football

3 Traits of a Bob Diaco Defense

January 16, 2017
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There are a lot of ways to build a defense, but how has Bob Diaco chosen to build his? I went digging through the numbers to try to get to what seemed like the most elemental parts of his Notre Dame defenses from 2010 to 2013. I chose to focus on those four years when Diaco was a defensive coordinator at a Power 5 program as those seemed like the closest analogue to what he will be asked to do at Nebraska.

The Irish put up some pretty good numbers across the board and had some high-level talent spurring them along, but when it comes to "traits" of a Diaco defense, I settled on three:

1. "No Crease" is No Joke


Diaco's defense has come to be known as the "no crease" defense, which loosely  means fill the gaps to eliminate horizontal creases, don't be overly blitz reliant to avoid vertical creases and remain assignment sound. The goal there being to prevent the big play. Every defensive coordinator would probably prefer to play that way, but Diaco did it at Notre Dame.

Between 2010 and 2013, the average college defense gave up an explosive play (20-plus yards) on 6.16 percent of its total plays defended. These were Diaco's numbers at Notre Dame:

2010: 5.31
2011: 3.95
2012: 4.34
2013: 3.66

Nebraska's numbers under Mark Banker:

2015: 8.70
2016: 5.96

Taken as a four-year chunk, Diaco's Notre Dame defenses gave up an explosive play 4.31 percent of the time. That was second nationally during that span, trailing only Florida State and one spot ahead of -- drumroll, please -- Iowa.

To put this another way: Between 2010 and 2013, Notre Dame gave up a 20-yard gain once every 23 plays. The average drive in college football is about six plays, so that's nearly once every four drives. Nebraska during the Banker years gave up an explosive play once every 13.6 plays, or about one every two drives.

Preventing the big play has taken on increased importance in college football as rule changes and offensive innovation have made for a more free-flowing game. The defense that can prevent them is the defense that's the best off and this feels, and the numbers bear it out, like one of the founding principles for Diaco.

2. Red-Zone Defense


The average red zone trip over the past seven seasons of college football has been worth 4.88 points for the offense. Down that close to the end zone, there are only three possible outcomes -- touchdown, field goal or a stop -- and only one of them is an outright win for the defense. Diaco's Notre Dame defenses were better at getting those uncommon wins than most.

Here are the red zone points per trip for Notre Dame. Anything in the low-4s is very good.

2010: 4.10
2011: 4.77
2012: 3.42
2013: 4.52

Taking those four years together, the Irish allowed 4.24 points per trip under Diaco, which was second nationally over that span. Only Alabama was better at an insane 3.75 clip.

Diaco shouldn't have to start from scratch in this category with what he inherits at Nebraska. The Huskers were slightly better than average in 2015 (4.73) and slightly below average (5.15) in 2016. But the most encouraging sign for Husker fans here might be that red-zone defense feels like more an identity change than a schematic one.

Like big-play prevention, there are some things you can do in terms of personnel and risk-taking (or lack thereof)  to help improve the numbers, but a lot of it still comes down to mindset. I feel as though Diaco could have walked into his first meeting with the Huskers and said, "Here's what we're going to do, prevent the big play and try to win in the red zone," and that would not have been an inaccurate encapsulation of his past defenses nor an unrealistic way forward for Nebraska in year one. Those are achievable goals, particularly if they are fundamental tenets of the defense right from the start.

3. Turnover Independence


Remember when Bo Pelini returned to Nebraska and many people pointed to Pelini's insane number of takeaways during his year as defensive coordinator? I'm sure I probably did it as a way to make a point about "ball-hawking defense." That never really materialized. Three of Pelini's seven Nebraska teams ranked 91st or worse in total takeaways. Three more ranked in the 40s. The 2009 team was Pelini's best at 21st nationally.

That's because the idea of a "ball-hawking defense" is a myth. Turnovers are too random to be consistently controlled. The coach that could eliminate giveaways and create takeaways year in and year out would be worth his weight in gold.

(Interlude: How much does the average football coach weigh? Conservatively, let's say 210 pounds based on the fact that many of them are former players and thus big, athletic types. At the current price of gold, that's only $4.05 million, which 20-plus coaches already make per year, so let's say "double his weight in gold." You'd pay Harbaugh money for the coach that had taken the randomness out of turnovers, maybe more. If I had access to coaches' weights, I would definitely create a spreadsheet to determine which coaches were literally worth their weight in gold and update it daily based on the fluctuating price. This would be known as the "gold club." For example, Kirk Ferentz would be worth his weight in gold at about 233 pounds, and I don't think he weighs that much, so he's safely in the club. Anyway.)

Because turnovers are going to remain random, the defense that needs them the least is the best off and Diaco's defense showed that tendency, too. Here are Notre Dame's  national rankings under Diaco in defensive FEI (a drive-based efficiency metric) and S&P+ (a play-by-play efficiency metric), followed by its national rank in takeaways:

2010: FEI: 11 | S&P+: 10 | Takeaways: 36
2011: 18 | 11 | 112
2012: 14 | 8 | 48
2013: 49 | 48 | 103

Those are some big swings in takeaways, but, for the first three seasons at least, not a lot of variation in the overall defensive rankings. Turnovers are always going to have an impact on a season, but the goal here should be high-ceiling, high-floor. The defense that is capable of producing in years when the ball simply bounces the other way is pretty valuable. And when the ball does bounce the defense's way, those seasons have the potential to be off-the-chart type seasons.

We didn't get to see one of Diaco's defenses at Notre Dame with a top-20 number of takeaways, but the key point is that he was able to churn out good defenses anyway. Unlike preventing big plays or red-zone defense, being perfectly average in terms of giveaways isn't something you set out to do but, based on the numbers, being "turnover independent" should qualify as a trait of those Notre Dame teams, too.

And, if those traits carry over to Nebraska, well, the Huskers' may have made their best hire in recent memory.
 
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