If you watch the OLine Committee, they explain how it works on the OLine, and turns out, it's extremely complicated. "If Bradford feel the Center bump on the player he's blocking, generally that means "Go ahead and help the Tackle. " But on the play in question, Sundell had yelled something to Bradford, but the audience was still screaming from a great run back, and they don't thing AB heard him.
There are so many rules, and that is why continuity is so important. Keep "AB," bring in competition that has experience in this offense, and let him compete.
Despite all of the cherry picked bad plays AB had, he has played very well most of the time, and you can NOT match his power. He erases DTs and Edges sometimes, and blows up the 2nd level when he's on, which is most of the time.
IMHO, we have too many needs to be focusing on a guard.