Good post, these are similar points that myself and others have been posting for quite awhile.
One thing about Trent Dilfer though, he is the exception, not the rule IMO. The 2000 Baltimore defense will probably go down, if not already, as one of the most dominant defenses of ALL TIME...not many defenses better then that bunch.
More often then not, to win a SB you need to have your QB do more then manage the game, more often you need to make sure your QB can MAKE the big plays at crucial situations during a game and STAY AWAY from critical mistakes as much as possible (see Jake Plummer as an example of a guy who cannot shake that).