Everybody wants us to jam it up in there on 3rd/short, but the back is not the problem, imo.
Despite Chan's excellent design, teams do not fear the Bills air attack because our WR corpse is just awful, we only have 1 marginal TE and Fitz is a gutty top level backup. As a result opposing defenses are wildly attacking the LOS with little fear of what's going on behind them; watch that game tonight (or any week) and look how much pressure teams throw into the trench on every down, especially short yardage downs. This OLine is not built to overpower people, it's built with smart agile guys who understand angles and sustain blocks in space. They simply do not have the personnel to line up and knock people off the ball and it doesn't really matter which back they try to do it with.
Hell, I think Brad Smith is a very crafty short yardage ballcarrier but even when you go Wildcat and play for a number advantage (that you still don't really get) we still have to fight to get that yard.