I have noticed the Bill's D seems to crumble when there is a balanced offensive attack. Big gains seem to come when they don't know whether a run or pass is coming. If the Vikes try to be too one dimensional, the Bills D will have some big plays.
In this particular case it was W W L. 2 steps forward and 1 step back. This team knows they had the Steeler's backs against the wall and will be the spoilers for the upcoming playoff season.