LOL!!! I think the reason for that is he had some ridiculous games. I'm pretty sure that Thanksgiving game against the Lions started it all. Where he made a series of plays that not only brought the team back, but won the game. Not just one play, several. He won that game by himself.
Then if not for him, the Giants don't go to the SB in 1990. But yeah, when people talk about him now, he was the reason the Giants won every game that they did. His legend has gotten to the point where no one can ever be as good as him.