Seattle falls two spots this week despite winning in Carolina. Their passer rating differential is still negative, and their point differential is not big enough to make up for it. Arizona, sitting at 6-1, is still ranked lower due to a much weaker strength of schedule. People have questioned the Eagles low ranking, rightfully so, but they have a significantly negative passer rating differential and a poor SOS.
Detroit looks like another pretender with a very poor SOS and small point differential. Watch out for the Saints, who are showing signs of life. Their game against the 49ers in a few weeks will be telling. Four of the Seahawks remaining nine games are against teams ranked ahead of them, while six of nine are against top fifteen clubs. Those choosing to place a bet on these games will certainly have to do their fair share of research. The bunching of teams, as shown in the scatter chart below, is unlike most other seasons. The difference between #4 and #13 is very slight.
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.
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 was simple, I measured 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” was 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, but I am always looking for ways to improve it. I read a great article on ColdHardFootballFacts.com. There was one gem in there about predicting championship teams. The article mentioned passer rating differential as the “mother of all stats.” A full 69 of 72 champions have ranked in the Top 10 in this statistic. It is a stat after my own heart, as I believe offensive and defensive efficiency is the key measurable outside of point differential. Turnovers would factor in there as well, but I am not convinced a team has as much control over that. My power rankings use YPA and YPC differentials. I went ahead and replaced the YPA with offensive and defensive passer rating, to give me this:
(YPC (offense) + Passer Rating (offense) + Avg Pts/Game Scored) – (OPP YPC (defense) + OPP Passer Rating (defense)+ OPP Avg Pts/Game)
As of September 23, 2014, I have added a strength of schedule component to the rankings as well.