Seed advancement probabilities

File this under “bracket pondering essentials.” If you’re going to use seeding as a guide to making your picks—and you should—you’ll need to know each seed’s probability of advancing from one round to another. These probabilities don’t take any factors besides seeding into account, so they won’t help you decide whether that three seed with the abnormally high KenPom efficiency number is worth picking over a one seed. But they will show you the folly of picking, say, a 4v13 first-round upset or advancing any seed lower than a six too chart.

Take a gander at this graphic and the chart below. The picture illustrates the dominance of top seeds in the dance:


These numbers reflect the percentages of a given seed that survive from one round to the next. Take top seeds. Every one of the 112 that have competed since 1985 has beaten their 16 seed opponent. Score 100% for round one to round two. (Please don’t tell me that round one isn’t round one. Let’s just call that business that happens before the 64-team bracket is set “The Great NCAA Money Grab Round.”) In the second round, 98, or 87.5%, of the 112 one seeds advance. And so it goes. Amazingly, more than 40% of one seeds get all the way to the Final Four.

Absorbing all the numbers takes a little time, but here are some things the stand out to me.

  • One seeds are more likely to reach the Sweet 16 than three seeds are to win one game
  • One seeds are more likely to reach the Elite Eight than five or six seeds are to win one game.
  • One seeds are more likely to reach the Final Four than 10 seeds are to win one game.
  • Even two seeds are almost as likely to reach the Sweet 16 as five or six seeds are to win one game.
  • While you may be tempted to advance a 10-13 seed past its first-round opponent, it really makes no statistical sense to send them any further.

And I’m about to argue that you should waste your time even considering picking anything lower than a 5v12 Cinderella. Heck, you have better odds of automatically advancing a three seed to the Elite Eight than of a 13 seed springing a first round upset.

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