My immediate reaction is to dismiss this post. However, there is some merit to this. I think Manning is the type that doesn't like to deal with a lot of adversity. Hear me out. He wants to win easily and smoothly. As of now, he is not really a competitor. A competitor is someone who can start a game poorly and compensate it for it later in the game. The best QB's didn't quit if they started a game poorly which Manning seems to do. He doesn't have that ability to forget his mistakes and move on.
I think part of this problem is Tony Dungy. I have a tremendous respect for Tony Dungy as a strategist and playcaller. I respect that he treats his players with respect and doesn't yell at them. But a good coach has to know when to yell at his players and stir up some emotion.
Tampa Bay won the Superbowl because of Gruden. Gruden took Dungy's players and added a swagger and sense of confidence and cockiness they lacked under Dungy. I think Manning needs some swagger. Aikman, Elway and Montana were all competitors. Even if they were down, they didn't consider themselves out of the game. Manning has had this problem since college. Even at Tennessee, he couldn't beat Florida and he never played well when they were down early in a game. I think Manning will eventually overcome this and become tougher with age.