no one could be dumb for 4 years.....there is more to it than that.........got to be.
When a guy switches positions a time or two, it makes a big difference. Sometimes the move just doesn't work out like it's planned. I had pretty high hopes for Mendoza as well, both at RB and at CB. IIRC he tried out WR for a little while as well. It's really too bad he didn't get put in a position to succeed because just looking at his numbers, it's obvious that he was one of the most athletic players on the team.
His position swaps illustrate to me that he was a HELL OF AN ATHLETE just not a good football player. The coaches knew he was a freak, just could not find a position that he could play effectively. God knows they tried; instead of writing him off they wanted to find a way to let him play. I've met Marcus, he's a good natured kid (man now) I don't believe a lack of positive attitude or work ethic was an issue. I believe he just couldn't translate his athleticism to football skills.
Must have been extremely gifted athletically if the staff thought he could play so many different positions! When you get moved you get stuck behind a bunch of guys already entrenched at that position. Guys who who knows the intracacies of the playbook and position. Tough to do IMO.