It's hard to argue the offense was performing at a high level even last year. One average year out of five isn't good enough.
The question on whether Kill was the key factor in the schematic limitation is an open one. The team played better in many ways the last 5 games of the year, and the offensive line injury issues limiting the run game are well known. Still, the line hasn't been dominant at any point during their tenure, and the QB recruiting and development has been average to below average. I love Mitch, he is our best option and has improved, but he's not a program changer.
Inability to do simple things like get plays in to Mitch are simply inexcusable. The Michigan fiasco is 100% on Limey in my opinion. Claeyes will never say that.