Actually, the football equivalent of sabermatricians have been publishing models for years now that defense hasn't been the reason why really offense wins championships.
I'll try to find that analysis. I'm not sure if i saw it on a stat site or whether when of my fellow math geeks (but professional math geeks) emailed it to me.
Think about it empirically. Ravens a few years back won on defense. Dilfer was the QB. Had to be the D.
Maybe last year. But it wasn't like they held their opponent down. The Niners scored, especially in the 2nd half.
The 49'ers won 5 SB's. One year they had a truly excellent defense. The rest. Good, yes. Great no. The Bears had one the best ever. They won one, but they scored 46 in that game. And, they scored well over 400 points that year. (BTW: As someone who watched that whole season, it's a myth that the defense gave the ball to the offense in great field position all the time. The Bears were second in the league in scoring drives of more than 70 yards.) So, even they were dominant because they were REALLY good on both sides of the ball, not one.
Patriots have won 3. Defense is as you said.
This study, which i hope to find, showed the defense gets you to the playoffs, but since most teams have at least an average defense, the real key to winning a championship is being able to score against above averave defenses.
Even the old schoolers like Tom Jackson now say offense wins championships.
GAC