Chuba was indeed vocal about his coach wearing an OAN shirt. Said he wasn't going to play for him or something. They purportedly smoothed things over when Gundy actually apologized to the team (which is a rare concession from these college FB coaches) for wearing it, claiming he didn't know about the network and that the shirt was given to him.
I personally think it's a little weird for Chuba to have done that, as I can't imagine saying I wouldn't play for a guy wearing a BLM shirt, but I get his dissatisfaction with that kind of stuff. That sort of stuff doesn't belong really anywhere near a sports team, IMO, especially from a coach, who is supposed to be uniting the guys rather than potentially dividing them. But the quick and public apology should have sufficed. That's at least taking ownership.
So anything where his head wasn't there is really on Chuba, IMO, but I think it was more the ankle injury (those are killers for RBs) and his line than anything, but I'm not there, so I can't know. I'm just going by Ockham's razor.