First off, it's never a fluke when you win the SB. You have a complete team around you and you played at the top of your game for an entire season + playoffs. It's incredibly hard to do that. To call that a fluke is insulting to every team that's won a SB.
Second, the guy has played in three SBs and won one. Seems to me like he got over the hump.
Thirdly, he's got a plethora of records for his position at the highest level and will go down as possibly the best ever to play at his position. Doesn't sound like a slouch to me.
It's ridiculous to sit here and say he has underperformed in his pro career. The guy has reached the heights that every guy in the NFL hopes to achieve. Let's leave it at that.