(YPC (offense) + YPA (offense) + Avg Pts/Game Scored) - (YPC (defense) + YPA (defense)+ Avg Pts/Game Allowed)
The formula has proven to be a pretty accurate predictor of success. Even in the first week of the 2008 season, 5 of the top 10 ranked teams were playoff bound. As with any statistic, it becomes more meaningful as the sample size grows. Usually, these become most meaningful after Week 3. In 2007, 9 of the top 10 ranked teams were playoff teams, with the lowest ranked playoff team coming in at #15. In 2008, 8 the top 10 were playoff teams, with Arizona being the lowest ranked playoff team at #19. I'm not sure any formula could have predicated their run.
If you'd like to see how teams rankings changed from 2007 to 2008, you can read more here.
I have switched over to sharing the rankings via Google Docs, so hopefully, they are still readable.
Without further delay, here are the first rankings of 2009. It is the first time that the Seahawks have ever been #1. Bask in the glow!