23. Matt Cassel
Bill Belichick handed Cassel the starting position after Tom Brady’s ACL injury in 2008. To his credit, Cassel played well. But this conned the rest of the NFL into thinking he was a reliable long-term starter. After a few seasons in New England, he was signed by the Chiefs. However, they discovered the hard way that he wasn’t the man they needed (via Bleacher Report).

Cassel and the Chiefs failed to deliver against the Ravens in the Wild Card Round. The quarterback completed just nine of 18 pass attempts and threw three costly interceptions. It didn’t help that the Kansas City defense was nonexistent on the day. He lost his place as a starter after this game because he wasn’t up to the job. Some lessons are harsh.