I think it's fair to give old man Manning credit for yesterday, he's absolute toast but he did just enough to allow the defense to win the game. No turnovers (besides the lateral, which is more Hillman's fault than anything), and threw a few nice TD passes.
That said, this is akin to the 2006 SB run that Manning had, where the defense handed him the Lombardi. Besides the AFCCG against the Pats (legitimately great second half by, to be fair) he was at best average but the defense was phenomenal. Same story here: he's doing 'just enough' to allow his defense to win the game.
Brady has shown, on numerous occasions, that he can make the huge plays when it matters most to win. Game winning drives over and over again, not many of those back-breaking, 2nd half turnovers that Manning's accustomed to. This has not been a 'debate' for a long time, for anyone paying attention. The fact that Denver's defense is ferocious and has given Manning another crack doesn't change that at all.