Long answer (but not that long) is you need both a strong offense and defense.
However, the conventional wisdom that "defense wins championships" is no longer absolutely correct. This would be the point where someone provides stats but I don't have the time to find any myself.
However, I recall a similar thread last year where this issue was raised, and stats were provided that showed that over the last 10 years, there were more great offenses that won the SB than great defenses. I recall being surprised by that info.
Maybe in the modern NFL, with the changes in the game, it's better to build a great offense than a great defense.
That said, I don't believe any teams that won it all or went deep into the playoffs were weak on either side of the ball.
