Former Connecticut head coach and Notre Dame defensive coordinator Bob Diaco is expected to be announced as Nebraska’s new defensive coordinator. What are the Huskers getting in the New Jersey native and former Iowa linebacker? Let’s take a look at the numbers.
Diaco — who managed to coach at Eastern, Central and Western Michigan within a three-year span between 2003 and 2005 — landed his first defensive coordinator gig with the Chippewas in 2005. From there he spent three seasons as the linebackers coach at Virginia before becoming the defensive coordinator at Cincinnati under Brian Kelly. When Kelly went to Notre Dame, Diaco went with him and that’s really where he made his name as a defensive coach.
We’ll pick up the story in 2009. Here are the FEI and S&P+ national rankings for Diaco’s defenses from 2009 through 2013, his time as a defensive coordinator. FEI and S&P+ are both efficiency metrics that are published by Football Outsiders as well as at BCftoys.com and Football Study Hall respectively. For comparison’s sake, I’ve also included Nebraska’s rankings by the same measures over that span. (Hover over the individual data points for more information.)
What’s not shown on that graph is Diaco’s instant impact at Notre Dame. The Irish ranked 75th in FEI (a drive-based measure) and 39th in S&P+ (play-based) when Diaco arrived in South Bend, but jumped to 11th and 10th respectively. Notre Dame didn’t fall out of the top 20 for the next two years either, culminating in 2012, when the Irish allowed 12.8 points per game and played Alabama in the national championship game. Perhaps the best way to view this from a Nebraska context: Diaco’s best Notre Dame defenses were nearly the equivalent of the Huskers’ 2009 and 2010 defenses.
So what’s the profile of a Diaco defense? We can do a deeper dive on this at a later date, but balance is the word I’d use right now. Over the past eight seasons, including Diaco’s three as the head coach at UConn, his defense was better against the rush four times and better against the pass four times. His best defense (Notre Dame, 2012), not surprisingly, was the one that was best against the run, but the graph below shows that Diaco’s defenses can be a tough out either way.
Here are the national rankings for Diaco’s defenses in rush, pass and total defense (yards per game).
You can see that the UConn years featured some tough sledding. Diaco’s first defense in Storrs ranked 101st in FEI and 85th in S&P+, a slight step back from the previous season, but in year two he had the Huskies playing top-40 defense. UConn climbed to 32nd and 36th respectively, going 6-7 in 2015.
With five starters to replace in 2016, the Huskies dropped significantly but reports say Diaco’s firing at Connecticut came not from defensive struggles but because he wasn’t interested in hiring former Minnesota head coach Jerry Kill as his offensive coordinator, a move supported by the administration. Kill eventually accepted the same position with Rutgers. (That linked article is a rich one. Read it.)
I still have some questions about Diaco, but there’s little question in my mind that he was probably the best candidate available with college defensive coordinator experience. Nebraska went and got him.
We’ll have more on Diaco’s hire and what it means in the days to come.
