My conspiracy theory is he came late and Rams figured out he is too expensive so they already have moved on, but the team turned out better than expected and could actually win this year so now it will be interesting.
I think the coach boxes in the WRs in specific roles and Watkins is the guy that just practices sprints the entire game, going deep to clear out space. If he gets a few targets to keep the defense honest and makes a big play every 3rd game, that is all his role will be.
So, it is a combination of:
1) Came late to camp
2) Doesn't know the offense well
3) Rams don't think he will be signable so they kind of moved on to the guys that they know they will have going forward
4) Coach boxes WRs into specific roles and he has been put in a fit that doesn't utilizes his strengths. He is miscast as just being a speed guy that runs deep
But now that the team has a chance to win and make more money if they have a run in the playoffs and Woods is out, it will be interesting.
