Matt Cassel
The Patriots received the worst possible news in Week 1 of 2008 when Tom Brady tore his ACL. But it was a massive opportunity for Cassel because the backup stepped up into the hot seat. He had a 10-5 record as the team’s starting quarterback as he slotted into their system. However, that’s the crucial point because he became an overrated player.

Cassel did an effective job as their starter and that’s why Kansas City swooped for him after Brady’s return. But he was a cog in the Patriots’ well-oiled machine. The reality was that Tim Tebow could have looked like the second coming of Joe Montana on that team. In the end, Cassel proved that he wasn’t very good when he moved on (via Seattle Times).