R.I.P. to the R.P.I.: Selection Committee Breaks Out New Math

The Kansas Jayhawks entered the postseason with their wings clipped. Having lost two stars midseason — one to an N.C.A.A. suspension, one to unspecified “personal matters” — they could well sustain double-digit losses for only the second time in 19 seasons.

Yet according to the Rating Percentage Index statistic, which typically saturates bracketological prognostications ahead of the N.C.A.A. tournament’s Selection Sunday reveal, Kansas was, as of Friday morning, the top-ranked men’s basketball team in the country — higher than Kentucky, which beat Kansas handily in January; higher than Virginia, which had zero losses to teams not named Duke; higher even than Duke and its basketball messiah, Zion Williamson.

So should you start penciling Kansas in as one of the four No. 1 seeds before the bracket is released on Sunday night?

Not so fast. While you can still find websites that calculate R.P.I., the statistic is officially no more in the men’s game. The N.C.A.A., which created it nearly four decades ago, disowned it in the statistic’s most prominent sport last year.

And the R.P.I.’s myopic focus encouraged teams simply to schedule good opponents, or have the good fortune, shared only by major-conference teams, of facing many good opponents in league play. Worse, by not accounting for home-court advantage — in a sport in which the home team wins nearly two in three games — R.P.I. boosted teams that could afford to schedule more nonconference home games, which, again, tended to be major-conference teams.

“Depending upon the amount of money and support you have and your arena, you can basically isolate yourself from the rest of the world or at least control who you play and when you play them and where you play them,” said Doug Fullerton, who served on the selection committee when he was Big Sky Conference commissioner. “It’s a have and have-not situation.

Meanwhile, discouraging blowouts meant ignoring margin of victory, which sports analysts for decades have generally said is a better predictor of future winning percentage.

“When you played a good team, you didn’t get a bonus for winning by 40 than winning by 1,” Sokol said. He noted that Kansas has an unlikely 6-1 record in one-possession and overtime games this season, further explaining its aberrantly high R.P.I.

By contrast, NET factors game location into its Team Value Index, and the N.C.A.A. also sorts wins into quadrants based on whether they came at home, on the road or at a neutral court. And NET accounts for margin of victory, although in a nod to sportsmanship, the stat is capped at 10 points.

“I think that’s an honest attempt to try to capture what a point spread would tell you without creating an incentive for someone to run the score up,” Fullerton said.

To see the kinds of teams NET favors over R.P.I., and vice versa, consider two bubble squads: North Carolina State and Arizona State.

Despite playing in the competitive Atlantic Coast Conference, the Wolfpack had a dreadful R.P.I. of 93rd thanks to a schedule rated 120th-most difficult, according to Friday’s RealTimeRPI figures. That is partly the result of a conference slate featuring only four games against the A.C.C.’s top three teams — Duke, Virginia and North Carolina — and a nonconference schedule that began with five home-court gimmes. Yet with close road losses to the future low seeds Wisconsin and Florida State as well as wins over the likely tournament teams Syracuse and Auburn, North Carolina State’s NET is an eminently respectable 33rd.

On the other hand, Arizona State is a classic good R.P.I. team, having defeated Kansas and much of a middling — but R.P.I.-boosted — Pacific-12 Conference schedule. But there is much evidence that the Sun Devils are not that good. In the R.P.I., they were No. 35; in NET, No. 63. (They were No. 61 in KenPom’s rankings and No. 57 in Sokol’s L.R.M.C.)

Both teams are expected to claim one of the final at-large spots on Sunday. But if North Carolina State gets in while Arizona State is left out, it will be the surest sign yet that the Age of R.P.I. is over.

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