I’ve been trying to make some sense of college basketball’s Ratings Percentage Index.
I may as well be studying nuclear fission. It’s about as understandable.
The RPI has been around since 1981 and often has been used as an instrument by the NCAA basketball committee in its tournament selection process. The RPI employs a complex mathematical formula that roughly translates to (winning percentage times 0.25) plus (opponents’ winning percentage times 0.5) plus (opponents’ opponents’ winning percentage times 0.25).
It’s very complicated, sort of interesting and extremely flawed. You only need to look at the latest rankings to see that.
As an example, we compared the teams that are eighth through 13th among the 14 Big Ten teams on the RPI list as of Tuesday morning. To keep it simple, we excluded the seven Big Ten teams currently projected to make the NCAA tournament — Wisconsin, Maryland, Purdue, Northwestern, Minnesota, Michigan State and Michigan — and last-place Rutgers.
These are six teams all hoping to put together a big late-season run to get into the NCAA picture or at least maybe land in the NIT. Their RPI numbers could end up being very important.
Illinois, Penn State and Iowa all have the exact same overall record entering this week (14-12) and all of them have played similar schedules. They all played four top-100 RPI teams in non-conference games. They all have five or six wins against top-100 RPI teams, including Big Ten play.
Illinois is No. 71 on the latest RPI list, Penn State No. 73 and Iowa No. 105. Although Illinois is 13th in the Big Ten standings, it is the only team in the lower half of the standings that does not have any losses to teams not in the top 100. Iowa has one. Penn State has three.
Iowa may have lost to Nebraska-Omaha back in December, but Penn State lost to George Mason and Albany and became the first Big Ten team ever to lose to Rutgers at home.
The Nittany Lions do have one more victory against the top 100 than the Hawkeyes, but two of those wins are against that No. 71 Illinois team.
In short, it’s really hard to understand, how Penn State and Iowa can be 32 spots apart in the RPI.
The RPI becomes even more puzzling when you compare two other Big Ten teams with the same record.
Indiana and Ohio State both are 15-11. Both played four top-100 RPI teams in the non-conference season, but the Hoosiers’ four all are in the top 12 and they defeated No. 3 Kansas and No. 8 North Carolina. The Buckeyes also went 2-2 against the top 100 but their victories were over No. 68 Providence and No. 69 UNC-Asheville.
Each has one bad loss. Indiana was defeated by No. 158 IP-Fort Wayne while Ohio State somehow lost to No. 292 Florida Atlantic.
So how do you explain the fact that Ohio State 63rd in the RPI while Indiana is 91st?
The Hoosiers did play a lot of bad teams in the non-conference, facing six teams with RPI rankings 250th or lower. But Ohio State played five 250-plus teams and managed to lose to one of them. Makes no sense.
Then there is Nebraska, which has by far the worst overall record in the Big Ten at 10-14. For RPI purposes, the Cornhuskers are considered to be 9-14 because one of their wins came against a Division II team.
They did play more top-100 teams in non-conference play (six) than any of these other teams but they went 1-5 in those games with the only victory coming against No. 28 Dayton. They also managed to lose to three teams not in top 100, including No. 221 Gardner-Webb, and have only four wins against teams in the top 100. Even Rutgers has three.
But Nebraska is 86th in the latest RPI list, higher than both Indiana and Iowa.
The formula clearly has some big flaws.
A detailed look at the teams that are eighth through 13th in the Big Ten standings:
Ohio State – RPI 63
Overall record: 15-11.
Top 100 non-conference opponents (4): 14 Virginia, 23 UCLA, 68 Providence, 69 UNC-Asheville.
Top 100 wins (6): 25 Minnesota, 42 Michigan State, 58 Michigan, 68 Providence, 69 UNC-Asheville, 86 Nebraska.
Plus-100 losses (2): 105 Iowa, 292 Florida Atlantic.
Illinois – RPI 71
Overall record: 14-12.
Top 100 non-conference opponents (4): 11 Florida State, 27, VCU, 30 West Virginia, 79 Winthrop, 87 BYU.
Top 100 wins (5): 27 VCU, 34 Northwestern, 58 Michigan, 63 Ohio State, 87 BYU.
Plus-100 losses (0)
Penn State – RPI 73
Overall record: 14-12.
Top 100 non-conference opponents (4): 15 Cincinnati, 16 Duke, 54 Pittsburgh, 78 Georgia Tech.
Top 100 wins (6): 21 Maryland, 25 Minnesota, 42 Michigan State, 54 Pittsburgh, 71 Illinois (twice).
Plus-100 losses (3): 114 George Mason, 152 Rutgers, 159 Albany.
Nebraska – RPI 86
Overall record: 10-14.
Top 100 non-conference opponents (6): 3 Kansas, 17 Creighton, 23 UCLA, 28 Dayton, 39 Virginia Tech, 56 Clemson.
Top 100 wins (4): 19 Purdue, 21 Maryland, 28 Dayton, 91 Indiana.
Plus-100 losses (3): 105 Iowa, 152 Rutgers, 221 Gardner-Webb.
Indiana – RPI 91
Overall record: 15-11
Top 100 non-conference opponents (4): 3 Kansas, 4 Louisville, 8 North Carolina, 12 Butler.
Top 100 wins (6): 3 Kansas, 8 North Carolina, 42 Michigan State, 71 Illinois, 73 Penn State (twice).
Plus-100 losses (1): 158 IP-Fort Wayne.
Iowa – RPI 105
Overall record: 14-12.
Top 100 non-conference opponents (4): 14 Virginia, 26 Notre Dame, 47 Seton Hall, 55 Iowa State.
Top 100 wins (5): 19 Purdue, 55 Iowa State, 58 Michigan, 63 Ohio State, 86 Nebraska.
Plus-100 losses (1): 184 Nebraska-Omaha.