In this post-draft edition of Plugging the Holes, Football Outsiders will look at the largest remaining personnel needs of every team, going division by division.
Monday's edition examines the AFC East.
Buffalo Bills: Offensive line
The loss of Mike Pettine might prove to be a massive problem for the Bills next year. Pettine's arrival saw the Bills go from the 27th-ranked defense in DVOA in 2012 to the fourth-ranked defense in DVOA in the 2013 season. (DVOA is Football Outsiders' defense-adjusted value over average metric, explained here.) The unit also lost safety Jairus Byrd, though he only started nine games last year, when Buffalo had the second-ranked pass defense in DVOA.
It's on the other side of the ball where the Bills really have a problem.
Adding Sammy Watkins and Mike Williams to the wide receiver depth chart should help improve the passing attack, but little was done to improve the running game. Bryce Brown is a talented running back, but talent at the running back position can only take you so far when the interior of your offensive line is incapable of consistently creating running lanes.
Second-round pick Cyrus Kouandijo should start at right tackle, but he will improve the pass protection more so than the running game. Fifth-round pick Cyril Richardson and seventh-round pick Seantrel Henderson -- who was an offensive tackle in college -- will compete with veterans Kraig Urbik, Chris Williams and Doug Legursky for starting spots inside. A fully healthy C.J. Spiller, a hungry Brown and a very versatile Watkins should help the Bills revitalize their running game, but they need to get better performances from their interior offensive linemen too.