I'm not going to bash Goff, because he's not our QB.
What I've observed of him in Detroit is that he's no different than his last couple of years with the Rams. Same guy.
It's just that McVay seriously tempered his expectations and turned the offense into a half-horizontal field, roll-out, one read and throw, short passing offense. It's all that Goff could run. Campbell needs to understand that this is Goff he has and work around it for the remainder of this year.
It's why McVay was so beside himself. He knew he pretty much had everything else. So, when the rare opportunity to acquire an elite (or near elite) QB came along, McVay and Snead went all in.
I think Goff is simply what he is. He has lost confidence, courage, and the team around him is so lousy that he has no interest in getting clobbered to help it.
The problem Campbell is about to face (or already is), is that the team will lose respect and hope in Goff, and then what?
I also think Holmes was lulled to sleep on Goff because a) he helped to draft him and b) McVay propped Goff up in ways that few coaches would have.
All I can say is that the Rams made a great move in moving on from the regressing Goff and picking up a really good QB in Stafford. Now Goff is somebody else's problem.