1. Ryan Leaf
Career Years: 1998-2002
Career Lowlight: Having to be restrained from attacking a reporter in the locker room.
Any conversations about the biggest busts in the history of professional sports has to include Leaf. Remember when the Colts were trying to decide between him and Peyton Manning? We'd say they made the right choice; Leaf sucked from the start, throwing two touchdowns and 15 interceptions as a rookie in 1998. After missing 1999 with an injury, he didn't fare much better in 2000 as he threw 11 touchdowns and 18 interceptions. His follies off the field are even more legendary than his abysmal playing career, with arrests and numerous destroyed relationships with teammates making him one of the biggest jokes in NFL history.