Back in 2009, Notre Dame had a defense that was historically bad. Ranked 86th in college football, the Irish were allowing close to 400 yards per game on average. That is when a change had to be made and it began with new head coach Brian Kelly bringing over defensive coordinator Bob Diaco from Cincinnati.
Diaco installed his 3-4 defense and the team instantly began to see progress, allowing 358 yards in 2010, 344 in 2011 and then 305 last season. Last year the Irish had a defense ranked seventh in the country and it was critical to the team’s success in running the table and reaching the national championship.
But what makes Diaco so special? How can he just step on the field as a young coach and turn the defense around so quickly? He wasn't much of a household name a few years ago, but now he is considered one of the top assistant coaches in the country and has other programs keeping a close eye on him about becoming a possible head coach.
There is something really special going on in South Bend and everybody wants to know what it is.
Diaco runs a 3-4 style of defense that forces his players to be smart, athletic and versatile. If you understand gap assignments and if you can contribute in many different areas, there is a good chance you will succeed at Notre Dame. He wants his defensive line to be physical and take on multiple offensive linemen to make things easy for his linebackers, and he wants versatile linebackers that fly to the football and can defend the pass just as well.
While the amount of athleticism that is on the field would usually be enough to make a defense work, Diaco then mixes in tons of different looks. Again, the versatility of his players allows him to do many different things and switch things up, which confuses the offensive line and usually results in a mistake by the quarterback.
The players first must know their gap assignments. The weak-side defensive end is usually responsible for the B gap (between the tackle and guard). The nose tackle lined up over the center is going to penetrate the strong side A gap between the center and guard. Making things difficult for the offensive line, the strong side defensive end then runs through the B gap, forcing the right guard (Circled) to make a choice on who he is going to block. Somebody is going to be missing out here.
Unfortunately Michigan State was on the losing end of this type of play last year. With a defensive front that includes Stephon Tuitt, Prince Shembo and Sheldon Day, the Irish used similar gap penetration to get the sack.
Tuitt fills the hole between the guard and tackle, while Shembo takes the tackle head on but is making his way towards between the guard. Day is really lost out on an island on this play as it is a congested area in the gap that he is supposed to fill. However, due to the versatility and a high football IQ, he makes his way around the linemen and takes a clear path to the quarterback.
Due to proper gap penetration and a confused offensive line, Shembo ends up with the sack. And if it wasn't him that got to the quarterback, he had two of his teammates in on the action that would have easily been able to finish the job.
But Diaco and his defense doesn't stop there. He has a position called the CAT linebacker that usually acts as an extra defensive end. Sometimes rushing off the edge, sometimes playing with a hand in the dirt, this is where the linebacker position comes in handy. The outside linebacker known as the DOG is also used as a pass-rusher, but he spends much more of his time dropping back into coverage blanketing slot receivers and tight ends.
Not only does it add practically another pass-rusher to the table, but now we are talking about freeing up other players to come right through for the easy sack. Just checkout the sack that Manti Te'o handed Landry Jones in the game against Oklahoma.
This is your 3-4 front, but Williams is lined up on the strong-side as an extra pass-rusher (Circled). He will end up taking out the right tackle; opening up a hole you could drive a truck through for the middle linebacker in Te'o.
With an added lineman, the nose guard will now fill the A gap between the left guard and center, while the defensive end takes on the center and right guard. Again, players knowing what they are responsible for allows for a positive play. You can see Te'o coming right down the middle of the line untouched (Circled).
If all of this wasn't effective enough, it now allows for the blitz to come from anywhere as you just saw. It isn’t always the linebackers that are going to come up the middle. Sometimes it could be a cornerback coming off the edge like KeiVarae Russell did in the game against Purdue. With the offensive line having enough to handle, who in the world is going to block the freshman defensive back?
The answer is nobody.
Diaco has plenty of options on the defensive end because of the athleticism and the versatility his players bring to the table. With all of the linebackers being at least decent in coverage, anybody is able to blitz and anybody can drop back to play the pass. This allows Diaco to mix things up and it creates nightmares for the opposing offensive line and the quarterback. You don't know where the pressure is going to come from and you're not sure who is dropping back, if anybody at all.
This is a feisty defense that only knows how to play the game fast. He is going to throw many different looks at you and there is a good chance your offensive line is going to get confused at some point, allowing for a game-changing play for the Irish.
What he brings to the football field is only half the battle though. Diaco helped bring a culture change to South Bend, as he is a high energy guy and somebody who motivates his players to succeed at a high level. Much more than just someone who teaches the game of football, Diaco inspires his guys off the field, which translates to on the field success.
This is somebody who also has earned the respect of his peers, as secondary coach Bob Elliot told Angelo Di Carlo of WNDU just what he thought of the defensive coordinator.
There are some defensive coordinators that are great with X's and O's, maybe some are great teachers-- Bob is certainly both of those things. Elliott says. He goes well beyond all of that. He's a great motivator. He does a lot of team building.
It would be hard pressed for me to imagine there is a better defensive coordinator today than Bob Diaco.
When you bring the whole package to the table, it is almost impossible not to turn things around and immediately start producing. Diaco gets the job done on and off the field, which is why he has helped revolutionize this Notre Dame defense.
Note: All clips pulled from Youtube videos uploaded by user