After a fun year of Badger Bracketology, I wanted to reflect upon the college football playoff.
Nate Silver reflects upon the playoff in an article on FiveThirtyEight, and he touches on the two most salient issues in the playoff:
- False negatives: leaving teams with a credible case for being named the national championship out of the playoff.
- False positives: “undeserving” teams in the playoff.
As the number of teams in the playoff increases, the number of false negatives decreases (good – this allows us to have a chance of selecting the “right” national champion) and the number of false positives increases (bad).
One of my concerns with the old Bowl Championship Series (BCS) system with a single national championship game was that exactly two teams were invited to the national championship game. This was a critical assumption in the old system that was rarely discussed. There was rarely exactly two teams that are “deserving.” Usually, deserving is equated with “undefeated” and in a major conference. Out of 16 BCS tournaments, this situation occurred only four times (25% of championship games), leading to controversy in the remaining 75%. This is not a good batting average, with most of the 12 controversial years having too many false negatives and no false positives.
The new College Football Playoff (CFP) system has a new assumption: the number of “deserving” teams does not exceed four teams.
If you look at the BCS years, we see that this assumption was never violated: there was never more than four undefeated teams in a major conference nor a controversy surrounding more than 3 potential “deserving” teams. Controversy surrounded the third team that was left out, a team that would now be invited to the playoff. At face value, the four team playoff seems about right.
But given the title of Nate Silver’s article (“Expand The College Football Playoff”) and the excited discussion of the idea of the eight team playoff in 2008 after a controversial national championship game, I can safely say that most people want more than four teams in the playoff. TCU’s dominance in a bowl game supports these arguments. The fact that we’ve had one controversial seeding in one CFP is a sign that maybe four isn’t the right playoff size. What is the upper bound on the number of deserving teams?
Answering this question is tricky, because there is a relationship between the number of teams in the playoff and our definition of “deserving.” There will always be teams on the bubble, but as the playoff becomes larger, this becomes less of an issue. Thoughts on this topic are welcome in blog comments.
It’s worth mentioning the impact on academics and injuries. As a professor of operations research, I believe that every decision requires balancing different tradeoffs. The tradeoffs in the college football playoffs should not only be about false positives, false negatives, fan enjoyment, and ad revenue. Maybe this is trivial: it’s an extra game for a mere eight teams, but I will be disappointed if the entire impact on the student-athletes and their families such as academics and injuries are not part of the conversation.