You genuinely believe Brady is Brady without getting Hall of Fame defenses and the literal GOAT of placekickers to give him time to develop? You think Brady is still Brady if he had been drafted by the Lions?
Circumstances matter.
No one can say they expected Drew Brees to do what he did when the Saints signed him. He showed some potential at San Diego, but not first ballot Hall of Fame record shattering most ridiculous passer of all time potential. Brees needed an offensive mind who could build an offense that utilized his strengths. It was clear Brees eventually mastered his craft and put up absurd numbers regardless of who claimed to be the OC, but is Brees' the same guy he was in New Orleans if he goes to the Dolphins and has Nick Saban as HC?
All these guys need help. It is what it is.