Watson's biggest problem, in my opinion, is that he's lost a step or two. In Houston, he played with an equally bad offensive line early in his career. But he was able to create space with his feet and then look downfield for open receivers. Now, when he breaks the pocket, he gets run down by D-linemen and has no time to look for open receivers. And I think his arm isn't back to full strength.
That said, the Browns as a whole have significantly regressed. O-line injuries sure don't help. But it looks to me as if we have a big morale and confidence issue. We just aren't playing as hard as we did last season. I don't think that's Watson's fault, but I wonder what Cooper really thinks about Watson as a QB right now.