Kyle Williams has consistently proven to be one of the best defenders in the National Football League, since being selected by the Buffalo Bills in the 5th round of the 2006 NFL Draft. He’s been a mainstay at the defensive tackle position, but where is he going to line up in new defensive coordinator Mike Pettine’s defense?

The Bills have shuffled back and forth between the 4-3 and 3-4 defensive fronts for the past few years, and it’s expected that we’ll see quite a few 3-4 looks with Pettine calling the plays.

When the Bills decided they were going to use a 3-4 base package, they selected DT/DE Marcell Dareus out of Alabama with the No. 3 overall pick in the 2011 NFL Draft. Despite the fact that Dareus played the five-technique defensive end position in the Crimson Tide’s 3-4, it was expected that he would play nose tackle due to his large, stout and strong frame.

However, Dareus stayed at defensive end and the coaching staff decided to put 6’1” 295 pound Williams at nose tackle.

But why? Nose tackles are generally believed to be the biggest body on the field, capable of anchoring against blockers and allowing his linebackers behind him make plays.

However, there are two different styles of a 3-4 defense. A one-gap and a two-gap. The two-gap 3-4 defensive front is what people generally think of when they envision that particular defense. A monster nose tackle and two humongous defensive ends; each capable of swallowing up their oncoming blockers.

In a two-gap system, the nose tackle is responsible for occupying the center and usually the strongside guard. He lines up at the zero-technique (directly over the center), and his primary role is to make sure the offensive linemen don’t get a push.

On the other hand, there is the one-gap defense. This defense is used by teams like the Houston Texans and the Dallas Cowboys among others and has been very successful. In a one-gap scheme, the defensive linemen are still oversized at the defensive end positions, but the “nose tackle” is generally a smaller penetrating lineman.

In a one-gap defense, the nose tackle lines up as a one-technique (slightly off the center, over the strong-side “A” gap). With only one lineman to take on, rushing nose tackles such as Jay Ratliff are far more important to the scheme than a mammoth nose tackle.

The Bills used the one-gap 3-4 defense when Williams held down the nose, but everywhere Pettine has coached, they’ve played two-gap. The Bills currently have Alex Carrington, Marcell Dareus, Kyle Williams and Mario Williams on the roster, which presents decent flexibility for the team.

Williams is at his best when playing in the 4-3 as a defensive tackle, and his superior inside pass rushing would be put to waste in the bills’ new defense. He doesn’t have the strength or sturdiness to take on two blockers per game. Furthermore, if played at defensive end, he really lacks the power to fully set the edge.

While Kyle is undoubtedly the first or second best defensive linemen on the team, he may not fit the system that Pettine wants to run.