2025 College Football Analysis, Part One: 2024 Reflection

I have always been fascinated by the intersection of math and sports. Over the past several years, I have developed and refined a set of mathematical tools that I use to help me better understand the worlds of college football and basketball. With the 2025 college football season looming, it is time to open up the analytical toolbox and see what we can learn.

Before we dive into the upcoming season for the Michigan State Spartans and beyond, it will be helpful to review the results of the past season.

General Lessons from the Past

During the summer, college football fans and sports analysts have limited information. However, there is no shortage of various predictions about rankings, win totals, conference champions and College Football Playoff participants. But how accurate are these predictions, historically?

After studying this data for several years, the simple answer is that on average, the experts do a good job, but there is also a significant amount of variance. More quantitatively, I have developed these two rules of thumb:

1. The preseason rankings are accurate to plus or minus 25 positions (one standard deviation)

2. The preseason win total predictions (i.e. over/under lines) are accurate to around 2.0 to 2.5 games, depending on the year.

This information is helpful when looking at the preseason rankings and win predictions totals in July or August. Both data sets resemble a bell curve (i.e. a Normal or Gaussian distribution). The math related to this distribution tells us that approximately one-third of the teams will finish the season more than 25 positions above (or below) the preseason ranking and more than two games above (or below) of the preseason prediction.

But math also allows us to learn a bit more about the contributing factors that result in this deviation. The difference in ranking position is only semi-quantitative. But it is possible to dig deeper into the deviation in win totals.

I have found that the difference in the number of wins between the final tally and the preseason expected win total is due to three factors: changes in the strength of each team's schedule, luck and the expert's ability to accurately predict the strength of each team.

These three factors do not contribute equally to the final difference between prediction and reality. Here is another rule of thumb:

1. Changes in schedule difficulty contribute plus-or-minus half of a game (one standard deviation)

2. Luck (good or bad) contributes about plus-or-minus one game.

3. Differences in the perceived strength of a team in the preseason contribute plus-or-minus two games.

Some teams are luckier than others and some teams wind up playing an easier or harder schedule than expected. But the most significant impact on the accuracy of preseason predictions is simply that the experts do not have a firm grasp on how good or bad each team will be.

2024 College Football Preseason Polls in Retrospect

Based on this context, Table 1 below shows the teams listed in the last year’s preseason top-25 (and beyond), based on the consensus of the preseason publications, my final power ranking, preseason expected win totals (based on my calculations last summer) and final record.

The table also includes the results of my calculation of the impact of changes in ability, schedule and luck on each team's final regular season win total. These cells are color-coded depending on whether the impact was positive (green) or negative (red).