Power rankings are always debatable. I don’t buy into the gut feel methods most places use to determine their rankings, so I developed a formula a few years back that attempts to take at least some of the subjectivity out of the discussion. My approach is simple, I measure offensive and defensive efficiency based on the Yards Per Carry (YPC) and Yards Per Attempt (YPA), as well as points scored and points allowed. The formula to calculate “Team Strength” is as follows:
(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. Only 3 of the top 10 teams from week one of 2010 made the playoffs, and a team as low as #27 (Atlanta) was a league power. 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. In 2010 8 of top 10 teams from week 3 made the playoffs.
If you’d like to see final rankings from 2011, you can read more here.
History shows that a team strength score above 10.0 generally indicates a Super Bowl contender. Keep in mind that these rankings are best used to judge playoff spots, not necessarily predicting which team would beat another head-to-head. The difference between a team strength of 14.9 and 13.9 is not nearly as important as the general tiers of strength illustrated in the second chart below. Seattle dropped down to it’s lowest ranking in weeks.
Scatter chart of the rankings. This view helps to give you a view of how teams are grouped together. You will generally see tiers of strength develop as the season wears on. Note, the massive drop-off between the top seven teams, and the next tier.