I've been enjoying visiting the Football Ousiders' website
. They are the new home of Tuesday Morning Quarterback, Gregg Easterbrook's excellent weekly column of observations on the football weekend.
They rate the teams via a method that involves analyzing play by play data. I happen to think this is a great method, for reasons that I will get into later. However, for whatever reason, their rating system seems to be currently flawed, as best as I can tell with a limited amount of data. It may be that time will prove their system right, and my system wrong.
Let me start by explaining my system. Each game for every team is adjusted to an equivalent score against an average NFL team on a neutral field. For example, the week before last San Francisco beat the Rams at home by a score of 30-10. The spreadsheet notes that St. Louis has scored 1.281 times as many points in all its games as an average NFL team. Therefore, San Francisco's giving up 10 points to the Rams is like giving up 7.8 points to an average NFL team (10/1.281). Since the game was in SF, we add an additional point for the home field advantage and say that San Francisco's defense performed equivalent last week to giving up 8.8 points to an average opponent on a neutral field. St. Louis’s defense has given up .956 times as many points this year as an average NFL team. Therefore San Francisco's 30 points scored is equivalent to scoring 31.4 (30/.956) points against a normal team, adjusted to 30.4 points on a neutral field... to be continued...