Elias Sports Bureau produced a list showing lowest career winning percentages by quarterbacks drafted first overall.
Why do some highly drafted quarterbacks fail while others succeed? ESPN's Chris Sprow analyzed the subject with an eye toward quarterbacks who enjoyed success after spending one or more seasons as a backup.
My thought: Quarterbacks forced into lineups right away generally have worse supporting casts than quarterbacks afforded time to develop in the shadows. The former group would often be very high draft choices. Their teams were horrible the year before, which is why those teams drafted a quarterback early. Their teams threw them out there right away and the supporting cast wasn't good enough. Teammates lost confidence in the player.
So much of a quarterback's success depends on what's happening around him. Jay Cutler was legitimately an up-and-coming quarterback when he played for Mike Shanahan. The dynamics changed when the Broncos fired Shanahan, and Cutler probably will not recover until the dynamics are right again.