Conference Performance in the NCAA Tournament, Part 1

This is part one of a two-part series examining conferences in the NCAA tournament. Part two can be found here.

The 2016 NCAA Tournament field has been released, and this year’s field is heavily saturated with teams from the top conferences in college basketball. The ACC, Big Ten, Big 12, and Pac-12 all placed seven teams in the bracket, and overall only nine conferences have multiple teams in the field. But historically, how have the conferences performed in the tournament? Let’s take a look.

All data in this article covers tournaments beginning with 1985, the year the NCAA expanded the field to 64 teams.

 A Simple Measure – Wins Per Year

Perhaps the easiest way to measure tournament success in a conference is by a simple average of NCAA tournament wins per year of the conference’s existence.

Wins Per Year

With the fracturing of the once proud Big East, the ACC now stands alone at the top of the charts, with about 9.5 wins per year. For this article, I will be treating the new Big East as a different entity than the original, although I have included the performance of both combined in the chart above.  The Big Ten is a clear second, followed by the Big 12 and SEC. As we move down the line, we see pretty much what we would expect: a progression from the power conferences, to the stronger mid-majors, and then into the single bid leagues.

One issue with measuring teams this way, though, is that conferences that receive more bids have more chances at wins. Similarly, conferences that get seeded higher receive get better matchups. To correct for this, we can examine how the conferences perform compared to what would be expected from their seeds. Who lives up to their seed assignments, and who falls short?

Comparing Against Expectations Based On Seeding

Using data from every tournament game since 1985, I constructed a model to project outcomes based only on the seeds of the two teams playing, and the distance each team traveled to the game location.

Then, I used two complimentary comparative metrics. How often did teams from a conference win compared to what would be expected? And how did teams from a conference do in terms of point differential, compared to projected point differentials? Win percentage against expectation is a better descriptive measure of performance, looking only at the outcome of games. Point differential captures more information about relative performance, which is helpful for spotting trends.

Finally, for this article, I will be classifying conferences into three different categories. Power conferences are the strongest seven conferences, which each send many teams to the tournament every year. The Mid-Major conferences are a group of six, who average between 1.5 and 2.9 bids each year. The rest are the “Single Bid” group, averaging less than 1.5 bids per year.

Power and Mid-Major Conferences

Against Expected Win %(1)

Against Expected Point Differential(1)

Shade of bars coincide to total number of games played by teams in the conference.

From looking at the data, we see that power conference teams tend to live up to the hype, and the mid-major teams tend to fall short of expectations.

For the power conferences, the new Big East and The American have the biggest deviations from their expected performance. In the first two years since the split, teams from the American have far exceeded expectations, while teams from the new Big East have under-performed. The American’s numbers are a bit inflated by Connecticut’s improbable title run in 2014, but it will be interesting to see if these trends continue in the future. The old Big East was one of the two most dominant conferences over the 29 years from 1985-2013, but the new Big East is not the same conference. It’s plausible that the committee overrates teams from the current iteration, due to the Big East name.

Among the other, more established power conferences, the SEC historically has the best performance against expectation, while only the Big 12 under-performs by both measures.

Meanwhile, the data suggests the selection committee consistently overrates teams from the Mid-Major conferences.   Indeed, no mid-major conference exceeds expectations in both wins and point differential. The Mountain West and Conference USA are the biggest underachievers by both measures, which does not bode well for Fresno State or Middle Tennessee this year.

Single Bid Conferences

Against Expected Win %, Single Bid

Against Expected Point Differential, Single Bid

Finally, are you looking for a Cinderella for your bracket pool? Maybe you should start your search with the five single-bid conferences that exceed expectations by more than a point per game. The Atlantic Sun, Colonial, Horizon, Ohio Valley, and Southern have historically produced scrappy underdogs. However, notice that only the Colonial and the Horizon have translated these improved point differentials into improved win percentages, winning 10% (Colonial) and 9% (Horizon) more often than average for their seed. These are the leagues that produced some of the most memorable runs in recent tournament history: George Mason in 2006, Butler in 2010 and 2011, and VCU in 2011.

But don’t jump on the UNC Wilmington/Green Bay bandwagon too quickly. As I’m sure some of you noticed, all three of those teams have moved to higher tier conferences in the past few years. Conference re-alignment has shaken up the landscape of college basketball – a topic we will examine more closely in part two.

Data from Sports Reference College Basketball

Data organized and compiled using MySQL

Visualizations made with Tableau Public.

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