If you look back over the last 10-12 years, you can see a notable difference in the number of elite teams that relied on a running game and (yardage) defense versus a passing game and a defense that was mainly focused on creating turnovers. The days of Trent Dilfers and baby Rothelisbergers winning Superbowls are gone, IMO. The majority of the successful teams in the NFL are driven by a really good QB and passing attack. Not saying it's a good thing, not saying it's a bad thing. That's just how it is now thanks to the rules changes we've seen. Like I said, a good defense will never go out of style (although what constitutes "good" may change), but its relative importance has slipped recently (in addition to special teams), and a running game has become all but completely optional.