I already believe Tom was the top QB of all time based on everything he did in New England, but people have argued that the credit belongs to Belichick. Or he played in a weak division. Or he’s a system QB that wouldn’t be nearly as successful somewhere else.
For Brady to go to a new team, at his age, and lead them to a Super Bowl in year one is incredible. If he loses, he is still the greatest with Elway and Montana a distant second and third. If he wins, it is just an exclamation point on the fact no other QB can compare to how great he has been.