Buffalo Bills defense: Kyle Williams' role key to hybrid scheme

Buffalo Bills fans have spent - and will continue to spend - months trying to pin down exactly what the team's new defensive scheme will look like under Mike Pettine. That work starts up front on the defensive line, where Kyle Williams is still the team's best player, and by a considerable margin. Fitting the team's best defensive lineman into a front is the best place to start when pinning down a specific scheme.

Kyle Williams

• Age: 29 (30 in June)
• Contract: Signed through the 2016 season. Has already been paid a $1 million roster bonus this season. Will make $3.855 million in base salary in 2013.

Williams has been stellar for a few years now, consistently excellent as a pass rusher and sufficient against the run. We know his playing style, too: the 6'1", 303-pound veteran is at his very best when he's getting off the ball first and penetrating gaps. Williams still belongs on the field for as many downs as he can handle, but he lacks the length and girth to play two gaps on a consistent basis. As such, you'll almost certainly see him continuing to do what he's always done: flip between three-tech and one-tech, playing one gap and trying to disrupt plays in the backfield. He may also see some work as a nose tackle, similar to the way the undersized Brandon Mebane (6'1", 311) is used in Seattle.

Marcell Dareus

• Age: 23 (24 in November)
• Contract: Signed through the 2014 season. Will make a fully guaranteed $2.23 million base salary in 2013.

After two up-and-down seasons to start his career, the Bills are banking on Dareus coming into his own in his third year as a pro. Much like Williams, he's been better as a pass rusher than defending the run, and it's particularly important for the Bills that he improve against the run this season. The 6'3", 331-pound Dareus is at his best playing one-gap techniques thanks to his size and elite-level movement skills, but he has enough length and width to play two gaps, as well - and did so collegiately at Alabama. That versatility could tempt Pettine into moving him all over the line this season, playing any and all techniques between zero and five. He's capable of it, but it might be prudent to limit that a bit until he becomes a more consistent football player.

Alan Branch

• Age: 28 (29 in December)
• Contract: Signed a one-year, $3 million deal in March. Deal includes $1.5 million in base salary for the 2013 season.

Within the next couple of weeks, we'll be hitting the film to study how Seattle used Branch over the last couple of seasons, and using that to project where he might best fit in Buffalo. The free agent addition gives the Bills an experienced and dependable player with size (6'6", 325) and some versatility to move around the front. He will still, in all likelihood, be third in the line rotation behind Williams and Dareus, playing alongside them in heavier fronts and spelling them in certain situations. More to come on this front.

Alex Carrington

• Age: 25 (26 in June)
• Contract: Signed through the 2013 season. Scheduled to make $630,000 in base salary in his contract year.

A 4-3 end in college, the Bills drafted Carrington with an eye toward developing him into a 3-4 end that could play five-technique. The team's plans to play a 3-4 quickly fell by the wayside, and in the two years since Carrington has bulked up to 301 pounds (at 6'5") and seen a steady increase in playing time, making some nice plays as a penetrating interior pass rusher. Now that Pettine is in town, don't be surprised if the coaches again toy with the idea of trying Carrington's hand at playing some five-technique end - even though it's looking like he might be at his best in a three-technique role. His will be an interesting story to keep track of this season, as there is some untapped potential here as Carrington heads into his contract year.

Torell Troup

• Age: 24 (25 in June)
• Contract: Signed through the 2013 season. Scheduled to make $575,000 in base salary in his contract year.

The 2010 second-round pick has not appeared in regular season action since the first half of the 2011 season, missing a lot of time thanks to a slow recovery from spinal surgery. He was drafted to be a true 3-4 nose guard - one that plays two gaps and lines up on the center - but didn't do much of that as a rookie before the scheme shifted on him. He'll need to prove he's healthy and capable of contributing if he's going to make the team in 2013.

Jarron Gilbert

• Age: 26 (27 in September)
• Contract: Signed through the 2014 season. Scheduled to make $630,000 in base salary in 2013.

Gilbert, a third-round pick once upon a time, has languished on practice squads and at the back end of active rosters throughout his four-year career - not just in Buffalo, but prior to that in New York, where Pettine was his coordinator. That familiarity could help him out, as could his positional versatility. But there hasn't been much to speak of on the field for Gilbert.

Jay Ross

• Age: 25 (26 in October)
• Contract: Signed through the 2013 season. Scheduled to make $480,000 in base salary in his contract year.

Ross, a former undrafted free agent, is built in the Williams mold (6'3", 319) and projects into the new defense in the same ways. He spent part of last season on Buffalo's active roster, getting onto the field for a whopping eight snaps.

Corbin Bryant

• Age: 25
• Contract: Signed through the 2014 season. Scheduled to make $405,000 in base salary in 2013.

Another former undrafted free agent, the 6'4", 300-pound Bryant has the size to play two gaps as a five-technique 3-4 end, and that's where he might have a shot at cracking the final roster: if Pettine plans to utilize those techniques in his system.

Izaan Cross

• Age: 22
• Contract: Scheduled to make $405,000 in base salary in 2013. Contract length unknown, but likely three years.

Cross was just added to the roster as an undrafted free agent from Georgia Tech. The 6'4", 300-pound rookie projects into the NFL much like Bryant was just described: as a 3-4 end that can play two gaps. He'll play defensive end in Buffalo.

Aaron Tipoti

• Age: 23
• Contract: Scheduled to make $405,000 in base salary in 2013. Contract length unknown, but likely three years.

Tipoti, an undrafted free agent out of California, is trickier to slot into the defense. He's easily the smallest defensive lineman on the team (6'2", 280). Initially, he profiles in the Williams mold - as a one-gap penetrator that utilizes his quickness - and he looks like a player that may be destined for the practice squad.

Outlook

The top four names on this list (Williams, Dareus, Branch and Carrington) are locks to make the team. It's tough to guess at how many linemen Pettine would prefer to keep, mostly because we don't know exactly what the defense will look like - six or seven seems likely - but beyond that initial quartet, there are a lot of unproven players battling for an undetermined number of positions. While there is stability atop the depth chart, there are a lot of question marks on the back end.

Within that group of players that will be on the field, you see the foundation for what the Bills will try to build defensively: the best player can't two-gap, and the other three can in theory, but none are true nose guard material. Expect the Bills to use a one-gap system in 2013, featuring Williams in one- and three-technique roles, with the other players filling in around him based on down and distance. Dareus will play a ton, Branch will be used frequently, and Carrington could easily carve out a situational role, as well.