Kelly and the d-line (and blitzers) like someone else said, I want to see serious pressure this year, as I think it will make a world of difference.
On offense, I'll go out on a limb and say Josh Boyce. I hope he returns some kicks, and hope he gets some snaps on the outside. He should have had two long touchdowns in PS (Mallet missed him wide open in the first game) and that extra burst he provides just gives me hope.
Not sure he'll even get on the field, but if he does, I'd like to see him stretch the depleted Buffalo secondary a couple of times.