John Huarte
When he was playing at Notre Dame, he only had one good season to his name. In his senior year, he served as the starting QB for the Fighting Irish and helped them win most of their games in 1964. After winning the Heisman, the two pro football leagues drafted him. He decided to turn down the Philadelphia Eagles of the NFL and commit to the New York Jets of the AFL. Unfortunately for him, they gave the starting spot to Joe Namath instead. From 1966 to 1972, he was only the backup QB.
Ty Detmer
In 1990, this guy gave us one of the greatest seasons of any college football QB. The BYU alum had 5,188 rushing yards to his name and made 41 touchdowns in 12 games. He had a great junior year, but many thought he was too small for pro football. In the ninth round of the draft, the Green Bay Packers picked him. Ty Detmer was the backup to Brett Favre and went on to play for four more teams after that.