The power rankings are based on the method of least squares, which is a standard approach for analyzing data. No model can predict the outcomes of games from week to week, but the least squares approach (which was invented about 200 years ago by the greatest mathematician who ever lived) is completely objective and probably as good as any approach for estimating power rankings. A discussion of the approach is posted along with the power rankings for every season back to 1945 at my website: Power Rankings