The Middle Game Ratings and its offshoot, the Predictive are based solely on head-to-head margin of victory. Each week's calculation is updated from the previous week's rating of the teams. The theory is that the team should play as their season's history shows. If the team does not play up to its expectation, its rating is dropped or raised accordingly.
For the Middle Game weekly ratings the median rating is representative of the typical game. The Predictive Ratings use linear regression to predict the teams' strength for the next week's contest. The Middle Game Ratings give a very good picture of how the teams fared through the season and which teams most deserve to go to bowls. The Predictive is not very effective in the early season but has done well in the latter part of the season as the teams become more of a unit. It is best to follow the Middle Game ratings the first half of the season before switching to the Predictive.