I think unlike every other position on the team, the WR cant be effective unless the rest of the offense is and that can tick someone off. Think about it. The line is of course in on every play, the RB is on most plays, the QB of course, and the WR has to rely on the line, the QB, and the RB just to give the WR one ball thrown his way. I think that could be a little mentally difficult to some people ... who knows.
Personally if I went into the NFL and was assigned to the Dolphins and they were 2-8 or whatever, I would want to leave too.