Not to oversimplify anything, but I move to basketball to make an analogy.
There has been a great debate over who was better, Russell or Chamberlin. I think Chamberlin had better statistics overall, but Russell' s teams had more championships by far while the two were playing in that era.
Maybe, it comes down to that.
Granted, one can argue Russell had better players around him and I have not researched that. And, maybe Auerbach was a better coach than anyone the Lakers had at that time.
So then, if a pivotal player's team wins championships, I would think that fact wins over over a pure statistical comparison to another great player in any sport. Teams are more than one player, but a dominant player has a way of stimulating the other players around him.
One can argue Brady's stats for yesterday's game were not mind-blowing, but he threw the passes he needed to, and his number of Super Bowl victories and championship games do count for a lot.