Every little bit helps! But I don’t think Brady ever needs much help in the motivation department, he’s motivated himself at an incredible level for the last decade-plus. I think it just boils down to competitiveness. There are thousands of athletes out there that have the size and talent to play professional sports. Some have enough to make it to the pros on their god-given talents alone, but the ones who are truly special are the ones who are competitive almost to an annoying level. A “do you really care who wins this stupid game of ping pong” level of competitiveness.
That, more than anything else, is what gets athletes to the professional level. Someone like Brady, who isn’t the most athletic, but has a year-round desire to push himself to absolute max, are the ones who can be great. Of course, even Brady has perfect height and hand size to be a quarterback. There is a certain level of size and athleticism that no amount of competitiveness can overcome. But guys like Wes Welker, Danny Woodhead, etc. just prove it’s not the size of the dog in the fight, it’s the size of the fight in the dog.