NCAA Tournament Upsets: Most Upsets and Least Upsets Ever

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March Madness is as popular as it is because of the upsets. Nothing brings otherwise neutral fans together better than rooting for an Ivy league school to beat a blue blood. This article ranks March Madness Tournaments by the most and least upsets ever.

Because of the excitement factor associated to upsets, this list of “most upsets ever” can also be though of as “best March Madness tournaments ever”. Similarly, the list of “least upsets in March Madness” can be roughly translated to the worst/most boring tournaments. To do this, we went all the way back to 1985 when the tournament expanded to 64 teams.

At the end, we talk a bit about our methodology and how we measured how many upsets a tournament had. A quick summary is contained here though. First, our method weights bigger upsets more heavily. UMBC beating Virginia in 2018 is worth more than a random 10 seed beating a random 7 seed. Second, quantity of upsets matter. For example, two 13 seeds winning in the first round is better than a single 14 seed winning.

Now, we present the top by March Madness tournaments ranked by upsets.

Most NCAA Tournament Upsets

The list below contains the top 5 most NCAA tournament upsets in a given year. Notice that many of these seasons happened in just the last few years

  1. 2021 (Baylor over Gonzaga)
  2. 2022 (Kansas over North Carolina)
  3. 2014 (Connecticut over Kentucky)
  4. 2013 (Louisville over Michigan)
  5. 1986 (Louisville over Duke)

We’re going to deep dive the 2021 NCAA Tournament in order to understand just how crazy this tournament was. But first, let’s discuss what a typical tournament was.

Average Upsets Per Year in March Madness

In our past article discussing how well conference champions do in March Madness, we looked at the average number of wins per seed. The low seeds just don’t win that often. The table below shows the expected number of wins for every team that is an underdog in the first round.

Seed

Exp. Wins

Seed

Exp. Wins

7

0.9

12

0.5

8

0.8

13

0.2

9

0.6

14

0.1

10

0.6

15

0.09

11

0.6

16

0.01

The teams between 7-12 seeds win about 0.75 games on average. Sometimes this means losing in the first round. Other times it means winning two games to get to the sweet 16. Less often – maybe every few years, a double digit seed makes the elite 8. Only a few times ever does a double digit seed make the final four.

Once you get past a 12 seed, the wins get really hard to come by. A 16 seed has only won twice ever. The 15 seeds winning is not unheard of, but it has only happened a few times. On average 1 of the 8 teams in the 13-14 seed range wins in any given year. They almost never win two games.

Now, lets look at the 2021 tournament to see just how many upsets there were.

The 2021 NCAA Tournament

This was the tournament of upsets. In the first round, 7 teams seeded 11 or lower advanced to the round of 32. This included #13 Ohio beating #4 Virginia, #14 Abilene Christian beating #3 Texas, #15 Oral Roberts beating #2 Ohio State, #13 North Texas beating #4 Purdue, and #11 UCLA beating #6 BYU.

The tournament saw a few other notable events. #15 Oral Roberts advanced to the sweet 16, a first for a #15 seed. #11 UCLA advanced all the way to the final four only to lose to Gonzaga (in one of the most exciting games I ever remember watching).

#11 seeds won 6 games total compared to their expected win total of 2.4. #12 seeds won three games compared to their expected 2 (headline by Oregon State making the elite 8!). #13 seeds won 2 games compared to their expected 0.8. #14 seeds won 1 game compared to their expected 0.4. #15 seeds won 2 games compared to their expected 0.36.

Every underdog seed overperformed. 11+ seeds won 14 games compared to their expected 5.75.

Least Upsets in March Madness

The list below contains the top 5 most predictable NCAA basketball tournaments. The first is head and shoulders above the rest in terms of “least NCAA tournament upsets”. They are:

  1. 2007 (Champions: Florida repeat)
  2. 2009 (UNC over Michigan State)
  3. 1993 (UNC over Michigan)
  4. 2004 (Connecticut over Georgia Tech)
  5. 1995 (UCLA over Arkansas)

To see just how boring some of these tournaments were, lets look at the 2007 tournament compared to what we expect. In particular, keep in mind how crazy the 2021 tournament was.

The 2007 NCAA Tournament

In the 2007 NCAA tournament, Florida successfully defended their title from the previous year. They defeated 2nd seeded UCLA. Filling out the rest of the Final Four was 1 seed Kansas and 3 Oregon. The early rounds were even more vanilla.

Remember in the 2021 tournament that teams seeded 11 or higher won an astounding 14 games throughout the tournament. In the 2007 tournament, teams seeded 11 or higher only won twice. 11th seeded VCU beat Duke in the first round and 11th seeded Winthrop beat Notre Dame in the first round. None of the 10 seeds won either. There were just no upsets anywhere.

Every single 1 seed made the elite eight! Three of the four 2 seeds made the elite eight as well. The only other team that made the elite eight was a 3 seed. If you submitted a bracket with this few upsets you would probably be laughed at.

Overall, 2007 reigns as the NCAA tournament with the fewest upsets in any tournament ever. Moreover, because of just how chalky it was, it will be difficult for any other tournament to break this record for a long time.

Methodology

We want our rankings methodology to reward certain tournaments for having

  1. Lots of upsets
  2. Significant individual upsets

For example, a 16 beating a 1 is a bigger deal than an 11 beating a 6. In addition, having the championship game be a 7 seed versus an 8 seed required lots of upsets along the way so this tournament should be ranked as “very unlikely”.

The metric used to determine the most/least upsets in March Madness is based on probability. One can compute the probability that a particular bracket happened by multiplying the associated to the outcome of each of the 63 games. For example, if a 9 seed beats an 8 seed, that is a roughly 50% probability. An 11 seed winning is less likely and a 14 seed winning is even less likely still.

Multiplying all these probabilities gives the probability associated to the particular bracket. The more upsets that happen, the lower the probability of that bracket. The bigger the upsets, the lower the probability of a bracket. The table below summarizes some data associated to probability of brackets.

Bracket

Probability

2007

1.1e-11

2009

5.5e-14

Average

3.5e-17

2022

1.8e-19

2021

2.4e-20

Published by jdashbrock