The days of calling Notre Dame a 3-4 defense are over. In fact, you’d have been wrong if you called the Irish a predominantly 3-4 defense last year. While opposing coaches looked to use the Irish’s odd-man front as recruiting ammunition to keep edge rushers from joining Bob Diaco‘s defense in South Bend, the reality — both last season, and likely moving forward — is that the Irish defense will spend more time with four down linemen than three.
Thanks to some impressive work led by friend of the blog and former Blue-Gray Sky contributor Pat Mitsch, a breakdown of every regular season defensive snap is a pretty illuminating look at just how the Irish defensive line operated. The Irish defense played 819 snaps on the regular season. Of those snaps, 453 of them had the Irish in a four-down alignment, or roughly 55 percent of the time.
Digging into those numbers a little bit deeper, a pattern emerges for the Irish defense. First, after a more than disappointing debut against the option in 2010, the Irish defense has kept options teams in check, mainly playing a four-man front. Against Navy, the Irish defense played 63 snaps, but all but one of them was played with four down linemen.
(More interesting, considering how dominant the Irish were in beating up the Midshipmen 56-14, Harrison Smith still played 60 snaps. That goes a long way towards telling you just how important Smith was to keeping the defense aligned.)
Continuing the Irish’s solid play against Air Force, Notre Dame played 84 percent of their snaps in a four-down set, likely only playing more base defense as the Irish developed their second and third string defense in a fourth quarter that saw the Falcons score 17 points.
The key swing player in all of this was Darius Fleming. In a three-man front, Fleming was basically never seen with his hand on the ground. But in four-man fronts, Fleming took the leading amount of snaps at both defensive end positions (48% and 35%), showing a diversity that’ll likely come in handy if he’s to continue playing on Sundays. If you’re looking for Fleming’s replacement as that swing player, it’ll likely be Prince Shembo, who spent the third-most time at both defensive end positions with four-down linemen, ahead of guys like Aaron Lynch and Stephon Tuitt, who both played more inside at tackle in a front-four.
The fact that the Irish defense played so well in 2011 without big seasons from Ethan Johnson and Kapron Lewis-Moore gives you an idea of just how talented this young defensive front will be moving forward. Johnson, who was limited with an ankle injury, only played 39 percent of snaps this season. Lewis-Moore, who was lost with a season-ending knee injury, played only 46 percent of snaps, after playing 75 percent of the snaps until his injury.
If you had to speak in generalities, it looks like the Irish prefer to take on traditional pro-style offenses with a three-man front while playing mobile quarterbacks or spread teams with a front-four. Games against Michigan State, Purdue, USC, and Maryland saw the Irish predominantly play three-down linemen. Against teams with mobile quarterbacks (USF, Michigan, Air Force, Navy and Wake Forest), the Irish played heavier with a front-four.
Either way, the Irish got strong play from Mike Elston’s unit along the defensive line, made even more impressive by the fact that major contributors like Lynch (53%), Louis Nix (47%), and Tuitt (34% even while missing three games), all took the first snaps of their college careers in 2011. With the Irish needing to replace four of their top five snap-takers on the defensive side of the ball, it’ll be up to the front line to carry the weight next season. Regardless of how many down linemen are playing.