Everything on offense comes into question due to that. This is the pain of the OL failing. When that happens you suddenly have a hard time evaluating WRs, QBs, RBs, everything is affected by them.
That said I do think there are specific problems that can be seen in spite of the poor OL. And overall I think Coen is demonstrating that his knowledge of the run game is deficient. So I think he has a lot of room for improvement even though we can't fully judge him due to the line.
McVay should be looking to improve the run game. Hire someone who has fielded a good run game at this level. Gruden is available on the staff but he's not a guy I think is knowledgeable with the run, like McVay he's more steeped in the pass game. He needs someone good at that I think, because he is never going to be a dedicated ground game caller which means the run must produce in limited snaps.
