I think the Bills plan is to get them in 3rd and long by getting backfield penetration and then tee off in the pash rush. They are willing to give up some in the run game to not get gashed on deep balls but right now they are giving up too much...mostly due to bad fills, bad angles and missed tackles near the LOS
The Bills are weird because while they get gashed in the run game too often, they also are among the league leaders in TFLs, so they actually DO stuff a good number of runs in a given game.
The issue is, too often they then allow conversions in those situations and then get gashed with a house call run...
Perfect example is Bucs in 3rd and 12 due to some good D, they convert on the play and then Tucker runs 44 yards for a TD on the next play.
They simply need to be a little better at getting off the field on 3rd down. They are better than last year when they were near the bottom of the NFL, I think they are 18th this year so around average, but improving that would go a long way toward improving the overall D.
Pass D has gotten much better since Poyer and Hairston have gotten in there and Bishop is taking a step...
Now we just need to do better and get off the field on 3rd down more often and I think you'd see a lot of the problems mitigated.