It's mind boggling that people think it's Petras' fault this thing is going south.
Even Brian Ferentz's...
What's BF supposed to do with this OL? There's literally no scheme that works when your OL is playing so badly that defenses can send 3 linebackers or safeties at will, with no threat of a run or short pass game (because of blocking).
Is Brian at fault for the depth problems? Partially, yes. But Nick Saban, Woody Hayes, and Knute Rockne put together couldn't out-scheme this OL and make Iowa score points when these guys have days like they did against Purdue and Wisconsin.