RPI just part of NCAA Tournament criteria, so why all the hate?

Written By Mike Decourcy
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There are some things that become pervasive at different periods in American history whose raison d'etre can be something of a mystery. Parachute pants or mullets or hair metal - how did we end up there?

Each of these fads is as difficult to understand as what has become a near-universal loathing of the Ratings Percentage Index.

All the cool kids crush the RPI.

Sometimes, I think they do it because the other cool kids do it.

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I bring this up now because while many long have considered Valentine's Day to be about cards and candy and romantic dinners and flowers - I've been on top of that, also, or else I wouldn't be into my fourth decade of marriage - I have long looked at Feb. 14 as the day when there have been enough games played nationally for the RPI at last to have sufficient data to make sense.

For those not hip to the metric that is used by the NCAA Tournament selection committee to measure achievement by college basketball teams, the RPI is produced by combining a team's winning percentage (25 percent), its opponents' winning percentage (50 percent) and the winning percentage of its opponents' opponents (25 percent). Victories are weighted differently depending on whether they are achieved at home, on the road or at a neutral site.

That's it. It's not exactly the scientific formula for rat poison. So why do people argue against it with such venom?

The committee does not use the RPI as a straight measurement of a team's value. For instance, Minnesota currently is ranked No. 25 in the RPI as calculated by Jerry Palm at CBSSports.com. The committee does not look at this, assumes the Gophers are the 25th-best team and automatically assigns them to the No. 7 seed in the Midwest Region. What the committee members do is judge a team by how it has performed against subsets of teams grouped by their RPI rank.

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Minnesota is 4-5 against the RPI top 50. Not bad. It has no losses against teams outside the top 100. That's good, too. Maybe this team would be a 7 seed. Maybe not. It also depends on how other teams have performed.

The committee could use a number of different metrics for this purpose. It has used the RPI partly out of habit as other numerical evaluations of teams have become popular in recent years. But another reason has been previous committee members' preference for a metric that does not incorporate margin of victory into its formula.

It's possible there are other, better metrics to be used in measuring the achievement of college basketball teams, even without factoring in the scoring margin and focusing only on the pure result.

If one examines the current RPI, though, its standings are not drastically different from the most popular system, the KenPom ratings compiled by statistician Ken Pomeroy. There's certainly not enough of a disparity to justify the vehemence of RPI opposition.

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The No. 1 team in the RPI on Tuesday afternoon was Baylor. KenPom had the Bears eighth. The RPI loved them because they owned 10 victories against the RPI top 50; KenPom was less enthusiastic presumably because their offense is not extraordinarily efficient.

That's not a huge disparity, either way. In fact, the KenPom and RPI ratings generally are fairly close. A dozen of the RPI's top 25 teams are rated within five places of their KenPom numbers. For instance:

Villanova: No. 2 in the RPI, No. 3 in KenPom.

Louisville: No. 4 in the RPI, No. 5 in KenPom.

Gonzaga: No. 5 in the RPI, No. 1 in KenPom.

Duke: No. 16 in the RPI, No. 14 in KenPom.

UCLA: No. 23 in the RPI, No. 18 in KenPom.

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There are seven whose disparities are 10 spots or greater; for example, Arizona is No. 6 in the RPI and No. 23 in KenPom. The RPI has Butler ranked No. 12 because the Bulldogs have a number of significant victories, including over Villanova, Cincinnati and Arizona. KenPom flatters them less with a No. 25 ranking, effectively because many of their victories come by narrow margins.

Of the teams in the RPI top 25, though, the average disparity with their KenPom ranking is 6.9 positions.

If you're gathering teams in groups of 50, do seven spots matter that much?

The NCAA recently invited some of the top college basketball statistical analysts to a meeting in Indianapolis to discuss replacing the RPI with a different, better metric. There's nothing with that pursuit. The coaches who requested the matter be pursued have an obvious stake in assuring that the best possible system be employed.

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The RPI could be better, or it could be replaced. It is too easy to game; there's a significant reward for a top team beating the 150th-best team in a November home game as opposed to the 325th, when in fact the power team is almost certain to win regardless. The smart teams pay up for the privilege. Those that are either not rich enough or are too cheap pay the price.

The system can be improved. No one's arguing about that. But the hate you'll see expressed for the RPI in articles elsewhere or on radio talk shows or podcasts, it just seems overdone at a time when so much love is in the air.