They say that QB is the hardest position to play well in all of professional sports, let alone football.
So, QB's tend to be the highest paid football players. And tend to get the MVP trophies.
We must ask ourselves whether this ranking is shaded more towards "most valuable" or truly "best" football players.
In any case, I think AD deserves a higher ranking than #15, but I am admittedly biased toward him.