I don't think his problem was mental ability. His problem was naivety. He grew up in a strict southern Christian background that saw any way but his own way as wrong and refused to compromise his beliefs in dealing with teammates. Sonny Jurgenson was hanging around the team and was befriended by Gus Frerotte, the genius that knocked himself out on a support column. You could see the discord on that team. OL were openly teasing Shuler, presumably with the backing of the Jurgenson/Frerotte faction, and what is worse, the worst coach in NFL history (Norv Turner) allowed this behavior on his team.