This is the first part of an eight-part series in which Football Outsiders looks at the biggest holes remaining on each team going into the offseason. Remember, some of these holes may not actually be holes if teams re-sign their own players, and other holes will be filled during free agency and the draft.
Today, Outsiders looks at the AFC East.
Buffalo Bills: Defensive end
The flirtation with the 3-4 defense for Buffalo lasted barely a year, just long enough to get defensive coordinator George Edwards fired, and now the team will turn to new hire Dave Wannstadt to undo the experiment and bring back a base 4-3. The move makes perfect sense, as it allows the Bills to line up their two best players, Kyle Williams and Marcell Dareus, side-by-side. That should give them the freedom to penetrate and make plays rather than requiring them to hold their ground and soak up blockers as they would in a 3-4. It's a move that should help stiffen up the interior run defense, which gave up 4.52 yards per carry on runs between the guards last year. It probably won't do much to generate more pass rush, however, as it's unreasonable to ask for Dareus to improve much upon his rookie total of 5.5 sacks.