There has to be no one in the NFL more frustrated than Peyton Manning.
Manning's neck injury has kept him out the entire season so far, and the Colts are 0-5 without him. The Colts are so bad Manning will likely be shelved for the season because by the time he comes back, the Colts' season will be over.
Manning has moved to the sideline to try to help, and the truth is the Colts have played better the last two weeks with Curtis Painter than they did with Kerry Collins. It still did not help as they have yet to win a game. There has to be nothing more frustrating than not being able to play to help your team and watching them free fall right before your eyes, knowing you could have helped, but your body is too beat up.
For that reason, Manning is an easy top choice for this list.