I think the best thing to do is be a realist and not fall on false hope. You say that if we start Watkins it signals to the league that Thomas, Abdur-Rahim, and Moore are terrible and makes them even more untradeable. Here's the truth, those 3 guys are terrible, the league already knows it, and they are as untradeable as they can possibly be.
As far as their attitudes go, I'm sorry but if I'm the coach I can't let that hold my team back. As I said before it's up to the other players to put those attitudes in line, if they can't then they can leave.
Finally, a contending team is not built overnight. We are certainly not a Watkins away from accomplishing anything but he is a piece, and Williams might be a piece. A couple good draft picks here and there and we have something. Here is what I know for sure, Thomas, Abdur-Rahim, and Moore are not those pieces.