The Buffalo Bills run a nickel defense as their primary personnel grouping, meaning that there is both an increased focus on linebackers and a decreased focus on the position grouping at the same time. Sure, that sounds contradictory, but it means that Buffalo may not need as many linebackers as some teams, but if their linebackers aren’t good, it’s incredibly easy to notice.
Just because the Bills are only playing two linebackers at a time for most of their defensive snaps doesn’t mean that the team can skimp on quality depth. In the defensive system Buffalo runs, the linebackers have myriad responsibilities, and they have to cover a whole lot of ground.