I disagree. Bill Belichick follows some simple axioms, that contribute to his success. Like, "God fights on the side of the heaviest Artillery"'. "Get there the fastus', with the mostus' ".
Drew Bledsoe was a very good QB, but he never had the heaviest artillery in his army. Do you remember the somewhat pathetic Defense that Caroll's DC had to conjure, annually? It reminds me of Wrecks Ryan manufacturing a Defense of Blitzes for lack of talented Pass Rushers. It works until all the blitzes are on tape, and the OCs study them a bit. It falls apart in the second half of the season, just like the Jesters do.
BB knows if he has the "mostus", and he gets it with his double drafts, and his willingness to carry multiple players who can excel in only one thing, and if he uses them in his "situation substitutions", he will have more; and he will win. BB believes in winning with depth, (the mostus'). It why his teams get stronger as the season rolls along. He can more easily absorb injuries, as he has the mostus'.
Brady profits from this. In addition to his big time power, Big Ten football talent, he usually had a pretty talented Pats team around him. Bledsoe spent most of his career with much less. Grogan had even less. And Parilli's supporting cast was just pathetic, as Holovak had to collect used gum bubble wrappers and string, as well as coach.
Sometimes the Coach and the team he constructs around you, is almost as important as the QB. Matt Cassell won 11 games as a inexperienced youngster who never threw a pass in college. But he was a still big time power, PAC 10, recruit, with the triangle numbers.
BB took Mallett because he could, just like he took Wilfork, who slid to him.