ridiculous. You already have a nice sample to compare him with: other football players; and another sub-sample: quarterbacks. All of whom go through the same yearly regimen of getting pounded to the ground every week and with their own fair share of injuries.
Suffering the same sort of hits as every other one of his peers, why is Manning the one that needs a vertebral fusion?
Why?
Because there is something about his body--as there is with any other human's body--that handles abuse and healing differently than others.
In fact, it is
exactly because he was injured this way that we very well know that his chances of suffering the same injury again, or even worse, is much greater than the average of his peers.