The Buffalo Bills will be moving to a "hybrid" defense under new defensive coordinator Mike Pettine - one that will operate under the premise of "attack first" out of multiple fronts. It's the type of defense that teams have to employ to keep up with evolving offenses these days. It also makes talking about what the team needs on that side of the ball somewhat confusing.

In order to potentially delineate what the Bills should be looking for defensively this off-season, we need to start from the beginning: determine the team's existing building blocks on defense (moving front to back), then fill in the missing pieces. It's very safe to assume that the Bills have three such players, and they all happen to be defensive linemen: Mario Williams, Kyle Williams and Marcell Dareus. Let's quickly review what each player can do best:

Mario Williams: He's best as a power end, playing either the six or the seven-technique on the outside of the offensive tackle. In a traditional 4-3 defense, this would mean he'd be playing on the strong side; in a hybrid defense, that would be far less commonplace. Williams can also drop into short zone coverage on occasion and play in space some, but has also said in the past that he doesn't prefer doing so; he could theoretically slide inside to play some three- or four-technique in pass rushing situations, as well.