Analyzing the Final College Football Playoff Poll
Throughout the college football season, I’ve been looking at the influence of the preseason AP Poll on rankings later in the season. Each analysis found a positive association between preseason rankings and the current rankings. That is, between top-ranked teams with a similar number of losses, teams ranked higher in the preseason are also ranked higher in current polls. The biggest exception is SEC teams, who were able to consistently jump over non-SEC teams who ranked higher in the preseason.
Now that we have the final college football playoff poll, let’s do one more analysis to see if the final rankings correlate with the preseason AP poll.
The Top 6 Teams
We’ll look at the top 6 teams that were vying for a playoff spot: Alabama, Oregon, Florida State, Ohio State, TCU, and Baylor. First we’ll look at an individual value plot showing each team’s preseason rank versus their final rank.
The only change from the preseason rankings is that Alabama and Oregon jumped ahead of Florida State. Other than that the final ranking of the teams is exactly the same as it was in the preseason. In addition, the correlation coefficient is 0.83 and there are 13 concordant pairs to only 2 discordant pairs. These statistics further show that teams ranked higher in the preseason will also be ranked higher in the final poll.
But to the committee’s credit, they did drop Florida State. This was unprecedented since Florida State went undefeated and Alabama and Oregon both lost a game. But all season long, Florida State has played close games against average teams. And whether you’re winning or losing, playing so many close games against average competition means you yourself are an average team. If this were the BCS era, the championship game would be between Florida State and Alabama, and we would all be howling about how Oregon got left out. But for most of the season, Oregon and Alabama have looked like the two best teams, and both will get their chance to show it on the field.
But are Alabama and Oregon really the two best teams, or is it simply confirmation bias? Before the season it was clear that pollsters (and I’m sure fans, too) thought Alabama and Oregon were two of the best teams. So by winning they simply confirmed a belief we already had. Imagine if Arizona had gone 12-1 and won the Pac-12 instead of Oregon, and Oklahoma went 11-1 and won the Big 12 instead of TCU or Baylor. Oklahoma started the year ranked #4 while Arizona was unranked. Any doubt the Pac-12 would have been the conference left out of the playoff in that scenario?
The college football playoff committee did set a few new precedents. As I noted, they dropped an undefeated major conference team behind one-loss teams for what has to be the first time ever. (I found it ironic that soon after the playoff committee did this, the AP and Coaches Polls did the same thing. They would have never done that before.) The committee also showed they wouldn’t be locked in to the prior week’s poll. In previous seasons, a team would only drop late in the season after a loss. But the fact that TCU dropped from #3 to #6 in the final two polls shows the committee isn’t locked into last week’s thinking. Whether you agree with the decision to drop TCU or not, this new way of thinking is refreshing. (And for what it's worth, TCU, the Sagarin Ratings still have you at #2.)
But when it comes to the top-ranked teams, it’s still better to have confirmed our preseason expectations that you’re one of the best teams than disprove our preseason expectations that you’re not. So Baylor, next year make sure to hire the PR firm before the season starts!