The problem with Couch is and always was a total and complete lack of confidence in himself. You know, people rag on Losman because some call him "cocky", but if Couch had even half of Losman's confidence in his abilities, Couch would be a Pro Bowler right now and the Browns would not be a cellar dweller.
I remember one Browns game where Couch threw an INT and then had this "oh well, its going to be another one of those days" look of frustration on his face. Good QBs get pissed when they throw INTs and want to get back in the game to correct their mistakes. Couch just gave up. A very sad story for him, that kid had no self-esteem at any point in his career.