Pre-Season Rankings

Hey football fans! The season kicks off in less than 24 hours – it’s time to get down to business!

First, here is a quick refresher on the rankings. I rank college football team using a statistical model and use the estimates of the relative team strengths to simulate the rest of the season 10,000 times. From the simulations, I am able to estimate … such as a team’s expected final record, probability of winning all remaining games, etc. I fit my statistical model under the Bayesian paradigm. In Bayesian statistics, you must specify a prior distribution for the strength of each team, which is essentially a prior guess as to the relative strength of each team. After each week, I update the prior using results for all games played up to that point and by the end of the season the prior has very little weight in the rankings. In my case, the prior is an average of the pre-season rankings from the preview issues of several college football publications, which is translated to points above or below average for each team. My pre-season rankings are based on only the prior distribution and are the starting point for the rankings over the course of the season.

Here are the top 10 teams from the pre-season rankings along with their prior rating, two measures of their strength of schedule, their expected final record and probability of going undefeated:

Rank	Team	Rating	Record	SOS1	SOS2	E(FR)	P(WARG)
1	LSU	24.6	0-0	4.3	0.064	9.7 - 2.4	0.037
2	USC	24.6	0-0	6.1	0.117	10.1 - 1.9	0.063
3	Alabama	24.0	0-0	4.1	0.049	9.5 - 2.5	0.022
4	Oklahoma	23.4	0-0	5.4	0.083	9.7 - 2.3	0.053
5	Oregon	23.4	0-0	1.7	0.172	10.4 - 1.6	0.079
6	Georgia	22.4	0-0	0.8	0.145	10.0 – 2.0	0.040
7	Michigan	22.4	0-0	6.2	0.062	9.3 - 2.7	0.018
8	Florida State	21.8	0-0	0.8	0.172	10.0 - 2.0	0.062
9	Ohio State	21.2	0-0	4.1	0.110	9.5 - 2.5	0.044
10	South Carolina	21.0	0-0	5.6	0.05	8.8 - 3.2	0.005

The top 10 is composed of the usual suspects, for the most part, with four SEC teams (LSU, Alabama, Georgia and South Carolina), two Pac 12 teams (USC and Oregon), two Big 10 teams (Michigan and Ohio State), Oklahoma from the Big 12 and Florida State from the ACC. SOS¹ is the average rating of a team’s opponents (higher represents a more difficult schedule), while SOS² represents the probability that an elite team (defined as a team that is 25 points above average) would finish undefeated given the team’s schedule (lower represents a more difficult schedule). Michigan plays the most difficult schedule among pre-season top 10 teams according to SOS¹, while Alabama plays the most difficult schedule according to SOS². Finally, the last column provides the probability that a team finishes undefeated. We see that USC and Oregon have the best chance of going undefeated, although, they both have less than an 8% chance of finishing undefeated.

Another way to look at the pre-season rankings is to consider the top 15 teams with the best chance of going undefeated:

P(WARG) Rank	Rank	Team	P(WARG)
1	24	Boise State	0.143
2	23	Louisville	0.120
3	5	Oregon	0.079
4	2	USC	0.063
5	8	Florida State	0.062
6	4	Oklahoma	0.053
7	9	Ohio State	0.044
8	6	Georgia	0.040
9	1	LSU	0.037
10	12	West Virginia	0.031
11	13	Clemson	0.024
12	3	Alabama	0.022
13	17	Wisconsin	0.020
14	7	Michigan	0.018
15	62	Ohio	0.018

Boise State always finds themselves on the top of this list because they have established themselves as a consistent top 20 program but play much easier schedule than teams in the power conferences. That was supposed to change when they joined the Mountain West but Utah, TCU and BYU leaving the conference means more of the same for the Broncos. It will be interesting to watch how Louisville’s season plays out. The Big East doesn’t get all that much more respect than the Mountain West and it is likely that they would be left on the outside looking in when it comes to the BCS Championship games even if they finished undefeated. Among BCS conference teams, Oregon and USC have the best chance of finishing the season undefeated, which isn’t surprising given the top heavy nature of the Pac 12. Finally, it’s worth noting that Ohio State is on probation and won’t play for the national championship regardless of their record due to a post-season ban. In fact, probation actually increases the chances that they finish undefeated because a post-season ban also eliminates the possibility of playing a tough game in the Big 10 championship game.  

As always, full rankings can be found at my faculty webpage: http://www.biostat.umn.edu/~josephk/index.php?page=sports. Enjoy the first weekend of the season!