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. 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 predicted their run.
If you’d like to see how teams rankings changed from 2008 to 2009, you can read more here.
The Seahawks remain steady at #11 this week despite giving up a ton of yards. The rankings formula accounts for games like that since absolute scoring differential is a much larger factor. Mike Vick and the Eagles made the largest climb, gaining 10.3 of their 10.8 Team Strength. We are through week 3, so these rankings start to take on real meaning. It’s likely 70-80% of the Top 10 will make the playoffs, based on history.
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 bunching between 5-12, and the dropoff down to 2 and lower.