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Purdue Football: Bob Diaco By the Numbers - La Tech

Previous Diaco defenses should give us an idea about what to expect in 2020.

Houston v Connecticut Photo by Rich Schultz /Getty Images

I’ve been mulling over the move to hire Bob Diaco as Purdue’s defensive coordinator since Jeff Brohm made the somewhat surprising move on January 2nd. I didn’t know much about Diaco. I had a vague recollection of him being mocked because of the “Civil Conflict” trophy rivalry he tried to start with UCF while serving as the head coach of UConn, but that was about it. I wasn’t exactly enthused.

A quick wikipedia search reminded me that he was the architect of the Notre Dame defense that lost to Alabama in the BCS Championship game. That was reassuring, but I still needed to do more research. He’s known for playing a 3-4 in college, which is fairly unique, but had no idea what to expect from his as Purdue’s defensive coordinator.

I’ve decided that the best way to get a handle on the future of the Purdue defense is to look to past Bob Diaco defenses. He’s served as the defensive coordinator for Louisiana Tech, Nebraska, and Notre Dame, so there is a track record to examine.

I wrote an article earlier for Hammer and Rails looking at the sheer size of his Notre Dame defensive line. In hindsight, Notre Damey isn’t the best place to start. That was several years ago and college football, and Bob Diaco (I assume) has changed with it.

I think the best place to start is the 2019 Louisiana Tech defense. Diaco was in charge of Skip Holtz defense for one season, and implemented his 3 man front (although he plays multiple fronts, the 3 man front is his base). He had to make do with what was on the La Tech roster to make his 3-4 defense work, much like he will this season at Purdue. In terms of size, the 2020 Purdue defense will look a good bit like the 2019 Louisiana Tech defense.

Defensive Line Comparison

2019 Louisiana Tech Defensive Line

LDE: Milton Williams - 6’4, 270

NG: Courtney Wallace - 6’2, 305

RDE: Ka’Derrion Mason - 6’4, 300

2020 Purdue Defensive Line

LDE: George Karlaftis - 6’4, 265

NG: Lorenzo Neal - 6’3, 315

RDE: Anthony Watts - 6’4, 300

As you can see, these are pretty close. In essence, Louisiana Tech featured a strong side defensive end (Williams), a nose guard (Wallace), and a defensive tackle (Mason). Purdue will feature a similar lineup with a strong side defensive end (Karlaftis), a nose guard (Neal) and a defensive tackle (Watts).

This bodes well for Purdue’s transition. Diaco featured 2 defensive tackles and a nose guard at Notre Dame, and Purdue doesn’t have that size. Based on last year at Louisiana Tech, however, it appears that Diaco is comfortable playing with less size on the line. Now, if we get into the depth, Purdue’s size drops way off, but in terms of the starting 3, this is encouraging.

Linebacker Comparison

2019 Louisiana Tech Linebackers

OLB: Willie Baker - 6’3, 250

ILB: Connor Taylor - 6’0, 225

ILB: Collin Scott - 6’0, 230

OLB: James Jackson - 5’11, 225

2020 Purdue Linebackers

OLB: Derrick Barnes - 6’1, 250

ILB: Jaylan Alexander - 6’1, 235

ILB: DaMarcus Mitchell - 6’4, 250

OLB: Jalen Graham - 6’3, 215

Again, Purdue and Louisiana Tech look fairly similar. Note that Jackson (La Tech) and Graham (Purdue) are actually safeties playing a combo LB/S role. La Tech last year, and Purdue this year, will run way more 3-3-5 than a true 3-4. Playing a smaller S/LB in one of the outside linebacker role gives you more options in coverage. Most teams line up 3 wide, so having a guy that can play LB or cover the slot is important. The downside is that you must protect the small linebacker in the run game, because if I’m an offensive coordinator, I’m finding the extra safety and running directly at him.

Inside, Purdue brought in DaMarcus Mitchell to be run stopper in the middle. At Louisiana Tech, Diaco went with small inside linebackers, but Purdue is going to face more power run teams. When Purdue plays against a spread look, I expect Mitchell to come off the field and Purdue to add and extra corner or safety.

When Purdue transitions to a 4 man front, expect Barnes to kick Watts inside and line up as a traditional defensive end. With the current personnel, Purdue can transition from a 3-4, to a 4-3 seamlessly, with Mitchell playing middle linebacker, and Alexander and Graham flanking him as outside linebackers. They can also transition to a nickel look from their base defense, with Barnes moving down, Mitchell and Alexander playing as dual middle linebackers, and Graham sliding out as an additional defensive back. The ability for Diaco’s defense to give multiple looks without having to substitute is something I’m looking forward to watching this season.

Secondary Comparison

2019 Louisiana State Secondary

CB: Amik Robertson - 5’9, 185

S: L’Jarius Sneed - 6’1, 195

S: Darryl Lewis - 5’11, 210

CB: Michael Sam - 6’1, 195

2020 Purdue Secondary

CB: Geovante Howard - 5’11, 185

S: Tyler Coyle - 6’1, 200

S: Cam Allen - 6’1, 190

CB: Corey Trice - 6’3, 215

First off, this is just a blind guess for the Purdue secondary.

I think the corners are correct, but there are several other players that could slot into the safety positions. I expect to see Cam Allen on the field a ton, but he’s going to be a guy that plays multiple positions in the secondary. If Purdue plays 3 corners, I expect Allen to be one of them, with another safety coming on the field. I went with Coyle, because he’s a grad transfer from UConn, and has played in Diaco’s system before (granted, only for a year). I don’t think you bring in a grad transfer to have him sit the bench. Just another guess on my part though.

That’s also one thing I want to note with the Louisiana Tech secondary. It was tough to figure out who was starting, and what position they were playing (I’m doing this off film b/c it’s surprisingly hard to find a La Tech depth chart from 2019). They played a bunch of guys in interchangeable positions in the back. I expect to see the same from Purdue this season. The safety position for the Boilermakers may be the deepest spot on the team, you’ll see several different combinations in the back end of the defense.

I’ll get into this a more when I look at stats and rankings of the Louisiana Tech defense last year, but Robertson and Sneed played a huge role in Diaco’s success last season. His scheme relies heavily on play makers in the secondary. Purdue has some potential in the back end, but it’s crucial for Trice and Howard (or whoever starts at corner) to be on top of their game.


Looking at how Louisiana Tech lined up gives me hope for the Purdue defense in 2020. The transition from the Holt to Diaco defense, in terms of size and position, won’t be as extreme as I feared. Initially, I worried that Purdue would be undersized, but La Tech played solid defense last season without having huge defensive tackles or linebackers.

Diaco beefed up the Purdue linebacker group by adding Mitchell as a JuCo transfer, but overall, he’ll have similar players to work with at Purdue in 2020 as he had at La Tech in 2019. The main question, of course, is Purdue’s ability to hold up against a power run game. That wasn’t a huge concern for Diaco at Lousisana Tech, because of more open style of play in Conference USA. Purdue has games with Iowa and Wisconsin, who love to pound smaller defenses. I expect a few other teams to test Purdue’s run defense as well. How the smaller Boilermaker lineup holds up in the Big10 may tell the story of the 2020 season.