let me ask it this way:
would you trade Kelly, Bruce AND Talley for Tom Brady? Assume that all 4 have full careers ahead of them.
Brady, by himself, is not worth all three. Would need to add Bellicheat to make that trade work. For all we know, Brady without Bellicheat ends up as a backup for the Raiders.
And its only one good year - Mahomes may have peaked for all we know.