Column: Include WAB in your bubble talk

Temple’s head coach Fran Dunphy has his team vying for the NCAA Tournament. Photo courtesy of Flickr Creative Commons

It’s almost March Madness. Selection Sunday is within three weeks. Soon, a favorite time for college basketball fans and media will be upon us: resume season.

Who deserves to be in? Who is out? Is KenPom gospel? Or are you more an eye-test guy?

This year, the NCAA accepted it was time to put its old evaluation measure of choice, the old and decrepit RPI, out to pasture. In replacement is the NET. The NCAA, like many powerful organizations, has chosen to be secretive about what makes up this concoction. We do know strength of schedule, efficiency and just pure old winning matter a lot. However, we don’t know just how much.

As Solving Basketball’s Jordan Sperber has pointed out, we don’t even know its true purpose. Is it supposed to be predictive—as efficiency metrics often are—or more of a resume—like the RPI was supposed to be?

Does it matter? As long as the NCAA is using it, yes, it does. Should it matter? Yes as well, but less than it ought to.

Rather than embrace the NET as the new be-all, end-all, I encourage all to check out the metric that is Wins Above Bubble (WAB).

I could try to explain it, but Jason Lisk of The Big Lead did it for us in 2015:

The idea behind it is simple. It tries to measure how likely a team is to win in each game based on opponent and venue, and assigns a probability. If a bubble team would have a 70% chance of winning a game, and our actual team wins, it is +0.3 wins above bubble. Over the course of 10 games, it would be expected to go 7-3.

The whole thing is oriented around exceeding the mean. In this case the norm is your standard fringe tournament team. Historical data is used to ascertain what such a bubble team is, and their underlying efficiency and statistics are used to create a replacement level team. Like WAR in baseball. That baseline is pitted against a prospective opponent from the current season, and the likelihood of a win is determined. Winning or losing adds or subtracts credit accordingly. If done right, it properly incorporates efficiency as well as quality of opponent and external factors like location and health that go into generating win probabilities. Yet it is still a measure of past accomplishment, like a resume, rather than a predictive measure, which, if utilized in candidacy for postseason play, I think it should be.

Metrics like KenPom aren’t assessments of teams, but really, they are prognosticating a team’s future performance to give it a value. WAB takes those same predictions, but for an average bubble team, and, based on the prediction of how they would do, assigns merit and value to a win.

Seth Burn, an analytics and sports betting man, calculates his own version as well as one for popular predictive measure like KenPom and Sagarin. Of course, those systems, including Burn’s, calculate win probability added. Who does it best is hard to say. Determining the best one would never be universally accepted, but if one were, it would create a baseline of expectations to work with. It doesn’t need to be accepted verbatim and used to slot teams precisely like the PairWise in college hockey. Rather it could just group teams by caliber like the current quadrant system and give a selection committee something to chew on.

A good case study and juxtaposition is this year’s Temple team. The Owls are fighting to make the NCAA tournament in Coach Fran Dunphy’s swan song, and ESPN’s Joe Lunardi has them in his bracketology, barely. KenPom is somewhat low on them, putting them at No. 71 prior to Monday night’s games. WAB has them at No. 46. What will happen with the Owls depends a lot on the next two weeks, but today, WAB would consider deserving of a bubble consideration while KenPom says meh.

KenPom became mainstream, and if the NCAA sticks with the NET, it will too. There is no reason that WAB couldn’t as well. Putting the most deserving teams in the NCAA tournament is important. When it comes to a hypothetical WAM (Wins Above Metric), WAB finds itself on the right side of this bubble in my eyes.


Matt Barresi is a staff writer for The Daily Campus. He can be reached via email at matthew.barresi@uconn.edu.