29. Peyton Manning
For many seasons, Manning was one of the best quarterbacks in the league. Then he got old and his level of on-field play plummeted. It’s a fact that for most QBs, the decline is not a gradual one. That’s exactly what happened to Manning. He was brilliant but his final season in Denver was appalling.

Manning went from throwing for the most yards and touchdowns in NFL history to injury after injury in the space of a year. In short, Father Time isn’t a great friend to anybody. But after such a stellar career, it was a shame for him to end things as a shadow for his former self.