Buffalo Bills 2015 NFL Draft needs: building D-Line depth

In their four years working together as a tandem, Buffalo Bills defensive tackles Kyle Williams and Marcell Dareus have weathered yearly coordinator changes and some growing pains, transforming from a duo with a lot of potential into one of the very best interior defensive line tandems that the NFL has to offer. During those four seasons, Williams and Dareus have combined for 49.5 sacks, five Pro Bowl bids, and one first-team All-Pro selection (Dareus, in 2014).

Clearly, the Bills are in pretty good shape when it comes to their interior defensive line with Williams and Dareus handling the bulk of the playing time. Why, then, is defensive line still considered a need area for the Bills in this week's 2015 NFL Draft?

Is there an instant contributor?

Rex Ryan is in town now (as is new defensive coordinator Dennis Thurman), and they'll bring with them a more diverse defensive scheme that will call for 4-3 Under base looks - and that alignment requires that a third interior defensive linemen be on the field, chiefly as a run defender. Last year, the Bills managed fairly well with Stefan Charles and Corbin Bryant handling the reserve defensive line snaps in a more traditional 4-3 defense, but neither performed well enough to be relied on as a nominal starter and run-defending specialist in the Ryan defense.

Any rookie defensive lineman that the Bills take early enough not only will have a chance to upgrade the Bills' current depth, they could wind up starting. Alan Branch held that two-down role in a similar Bills defensive system in 2013, and played just over half of the team's snaps. Neither Charles or Bryant cracked the one-third barrier a year ago. This is a big role that's up for grabs, and a talented rookie shouldn't have trouble moving past Charles and Bryant to lock down the gig.

Where does a project fit in?

Essentially, right alongside Charles and Bryant. If the Bills draft a defensive lineman - and they would be wise to, considering their reserve duo's 2014 struggles and Dareus' expiring contract next spring - said rookie would likely end up competing with Charles and Bryant for rotational snaps, even if they're not necessarily ready for a Branch-sized role.

Is it a need in 2015? 2016?

It certainly isn't their most pressing issue by any stretch, but the Bills could do a lot worse on the second day of the draft than finding a defensive lineman capable of stuffing the run and holding down a significant role in the Ryan defense.

That's just the 2015 outlook, too; in 2016, the Bills will be faced with handing Dareus a monstrous new contract if they want to keep him around, and Williams will be nearing the age of 33. If something goes amiss in the Dareus negotiations, or if Williams slows down at all this year (that doesn't seem overly likely at this point), that run-down rookie could be in line for a much more significant role in his second season. An early-round draft pick that fits both the short-term and long-term needs list is a good investment to make.