And there are outliers. KC had an incredible RB and ****e for QB. If anything it proves that running the ball alone won't let you win in todays NFL.
GB had huge Oline issues and ****e at RB so it all fell to Rodgers, not a horrible situation. That will let you win during the regular season but gets you exposed in the playoffs, especially if your D is underperforming.
What it shows is that we don't know. The Giants finished 32nd in rushing and won the SB 2011. The Ravens 11th last year. Green Bay 24th in 2010.
The Cards went to the SB in 2008 and never ran the football.
It's a combination of things not just getting a big lead that leads to good results rushing. Just like a lot of passing yards isn't just a function of getting behind and running up numbers in garbage time.