If every physically talented rookie QB magically learned how to stop making mistakes, then there wouldn't be any busts. Besides that, players who are CHOKE ARTIST don't usually learn how to not be choke artists.
I think you may be right on that. It would be interesting to see what former college QBs had a losing record or history of poor finishing abilities and were able to overcome in in the NFL. I honestly can't think of one off hand. Can anybody disprove this?