The Giants laid the blueprint...
Oh lord, here we go...
Look guys, if Manning fails on that last drive, the Patriots enter "Perfectville" with a 14-10 victory.
It takes a complete package to win a championship... despite all that pressure, Brady does manage several good drives, it's just that for a change, teams didn't just let Brady sit back there and pick them apart (see the Jags and the Chargers playoff losses)... the Giants decided that they were going to tee off on Brady no matter what the down/distance was, and assume that pressure would not give him time to throw the deep ball.
The otehr thing that was HUGE was Manning's ability to convert 3rd downs and keep the Patriots off the field. The Patriots had, what? Three possessions in the 1st half? That was equally huge, and kept the scoring down. The Giants, ironically, used a similar game plan to how they won Super Bowl XXV -keep the game close, control the TOP and don't give up the big play.
Brady's offensive line -depsite having three Pro Bowlers on it- had one of their worst games all season. Yes, it had a lot to do with the pressure from the Giants, but the Giants were not the first to do this to them. It's just in this case, they never did get on track.
And to the person who asked about the Steelers in the 70s... they had all-pros/HOFers all over that defense.
The Steel Curtain has now been attributed to their entire defense, but it originally was their defensive line: L.C. Greenwood, Mean Joe Green, Ernie Holmes and Dwight White.
However, in 1976, the Steelers had their greatest defense, but were unable to make it to the Super Bowl (losing to the Raiders in the AFC Championship game) because for most of the season, injuries plagued their offense. They went on a tear shutting opponents out, just to help their offense win.
Mel Blount's play from that season alone had a lot to do with the rule changes the league instituted in 1978 to open up the passing game.