An RPI with Road-Rage
12.20.04
Some of you may have seen the announcement in your local paper on Saturday. The RPI has been improved, now with 150% of your daily recommended road-game value!
The Division I men's basketball committee has altered the Ratings Percentage Index, used to evaluate teams for selection to the NCAA Tournament, to give more weight to playing and winning road games.
The RPI will continue to consist of 25 percent winning percentage, 50 percent opponents' winning percentage and 25 percent opponents' opponents' winning percentage. The new formula will weight each road win at 1.4 and each road loss at .6, while home wins are .6 and home losses are 1.4. Neutral-site games will have a 1.0 value.
Previously, all games were given the same weight. Committee chairman Bob Bowlsby said home teams have won approximately two-thirds of all games over the last 20 years. [Dallas Morning News, 12/18/04]
Previously, I wrote about the new formula. I've also written about Mr. Bowlsby's conclusion that because the home team has won 67% of the games over the past four years, that doesn't mean that road games are twice as hard to win as home games. By using the factors mentioned above, a home win is worth about 40% as much as a road win. This is not commensurate with the difficulty of winning a road game, especially for an at-large quality team, but they didn't ask me.
Now that the ingredients have been revealed I will be posting this version of the RPI on the main page. There is one possible bit of confusion. Will they do it the way I tested in that earlier post, or will they do it the way that makes sense? The way I talked about before is to only apply these adjustments to Part I of the RPI. The sensible way is to apply the adjustments to all three parts. To review:
Part I (25%) - Winning percentage.
Part II (50%) - Average opponents' winning percentage.
Part III (25%) - Average opponents' opponents' winning percentage.
I showed earlier what happened to last year's RPI when adjustments were only applied to Part I. Teams that were helped (or hurt) equally represented the power conferences and the mid-majors.
But when you apply the adjustments to all three parts, the results are what you would expect given the intentions here: teams at the top of mid-major conferences get a bonus. Teams in the middle of power conferences get penalized.
Here's how this formula would have affected last year's RPI
Teams most helped:
Austin Peay (94 in the basic RPI to 61 in the road-rage RPI)
Louisiana Lafayette (71 to 47)
Wisconsin Milwaukee (75 to 53)
George Mason (81 to 60)
East Tennessee State (61 to 42)
Illinois Chicago (87 to 69)
Troy State (66 to 49)
Murray State (58 to 41)
Air Force (70 to 54)
Western Michigan (44 to 28)
Nevada (29 to 14)
Kent State (76 to 63)
Pacific (65 to 52)
Utah State (43 to 31)
Power conference teams get killed by this formula. The biggest jump a team from a top-six conference made was four spots. Would this have changed the behavior of the selection committee? It's hard to say, but knowing that Utah State was the last team left out, you'd have to think they would have made it with a 31 RPI. Now the teams that were hurt...
Teams most hurt:
Virginia (52 to 84)
Georgia (48 to 76)
Rutgers (56 to 75)
Louisiana State (38 to 55)
Notre Dame (49 to 66)
Saint Louis (64 to 80)
Villanova (67 to 83)
Michigan (55 to 70)
Alabama (26 to 40)
Florida State (53 to 67)
DePaul (37 to 48)
Washington (60 to 71)
South Carolina (45 to 56)
At least this list makes sense. Most of the teams on here were considered overrated, they failed miserably on the road or padded their schedule with a ton of early home games. Now South Carolina's bid doesn't look so safe. If the new formula was used last season, it's possible, maybe even probable, that USC would have been replaced with USU in your brackets. With Notre Dame's presence on this list, I am obligated to reprint coach Mike Brey's reaction to hearing about the new formula:
"If we had that formula last year, we're a seven seed." [South Bend Tribune, 10/23/04]
Just saying it doesn't make it true, Coach B.
In 2004 - and I'd like to look at previous seasons when I get time - one mid-major school may have replaced a power conference school. While fans of the Gamecocks would not have been pleased with this development, the rest of America probably wouldn't have minded. Even someone like me, who doesn't buy all of the mid-major claims of discrimination, wouldn't have a problem with a mid-major bubble team getting the benefit of the doubt.
The wierd thing about the road-rage RPI is the mid-major schools get rewarded for road wins in their conference, which are easier to get than for the same caliber of team in a power conference. Utah State was the last team left out last season, and the reason was that their non-conference schedule was weak. So it's a little unusual that the NCAA is behind a formula that would have given the Aggies that last boost needed to get in the field because of their play in conference. Maybe this is an appropriate leveling of the playing field, though. I'm willing to have an open mind.
So, what's the bottom line here? Assuming that the NCAA is using this version of the calculation, this is a step in the right direction. Maybe a step too far, but a step nonetheless. I was never a proponent of tinkering with the RPI. Hopefully we have not just witnessed the beginning of the "BCS-ization" of the formula, where each year a new formula is used based on the apparent weaknesses of the previous season.
Defending the RPI, Part 3 of 3
12.26.03
This is the final post in a three part series. (The first two parts are here: part 1 and part 2). This one deals with how a lack of including home court advantage affects the formula. For the most part the effects are negligible. For one, most of a team’s schedule is made up of conference games that involve an equal distribution of home and away games. So the smaller non-conference part of the schedule is where a team can be unfairly rewarded or penalized for an imbalance of home or road games.
Sure, it’s easy to pick on a team like Georgetown that constantly plays a non-conference schedule of weak opponents at home. However, even if they played all of their games on the road, the competition has been so weak you might only expect one additional loss if that. Of their three losable non-conference games (Penn St., Duke, Temple), two are on the road. So they’re not a good example of a team that takes advantage of this weakness in the RPI.
Pitt’s schedule is similar to Georgetown, they’ve had a lot of no-risk wins on their schedule. Those are games that have been at home, but it didn’t matter where they were played, they were Pitt wins regardless. It’s hard to find any tournament worthy team where the imbalance in home (or road) games could make a significant difference in their RPI. Vanderbilt might be an example, but if they are really a top 10 team, then even the Indiana game being played at Bloomington wouldn’t have made much difference.
There’s always a cry from the mid-majors about the lack of "away-game disadvantage" in the system. But take a team like Toledo or Western Michigan that has tourney aspirations. Their non-conference schedules are loaded with road games. But as of 12/23 both have one loss. Even if all the games were at home, their record could only be improved by one game so far (Toledo still has to play at Louisville). Overall the complaints about home court advantage not being factored into the RPI are a lot of bluster.
The team that does the best job, year-in year-out, of abusing the home court advantage is Hawaii. It’s really no fault of theirs because they never have to schedule non-conference road games and they usually get some decent competition to come to the islands. This year they will have to head to the mainland to play in the Bracket Buster in February. But for the other 325 teams, the distribution of game locations doesn’t make enough difference to justify making a simple formula more complicated.
These posts were motivated by a discourse between Joe Lunardi and Jeff Sagarin last year in which Sagarin attempts to promote his own super-secret formula to replace the RPI. But college basketball does not need a super-secret formula - it hasn’t worked out real well for college football.
And considering its simplicity, the RPI is pretty good at what it's supposed to do. Winning games is good, playing a tough schedule is good. But more fundamentally, just being a good team is good. There’s really no easy way to cheat the system. And even if you could, there is a bunch of humans waiting at the end of the season to try to smooth out the problems.
Defending the RPI, Part 2 of 3
12.18.03
The previous post in this series addressed the myth that strength of schedule controls the RPI, while winning percentage is relatively insignificant. Now I'll examine the common complaint that merely playing "so and so" can lower or raise your RPI, regardless of the outcome. This is a statement that can't be refuted because it's true. And this post isn't really a defense, but a demonstration as to how the RPI works.
The effect of an RPI fluctutation merely due to whom one plays is obvious early in the year. By the end of the season this effect is reduced, but not eliminated. The RPI is only meaningful at the end of the year, so that's the perspective one should take when poking holes in it. And the RPI really only matters to a few teams at the end of the year, and those are the teams in the 35-70 range that are under consideration for the NCAA tournament. So for an example we should examine a bubble team's data at the end of the season.
Therefore let's look at the #43 team from last year, Gonzaga. They weren't really a bubble team, but their non-conference schedule provides more variety than anyone elses, so they are a great team to examine. Gonzaga played #1 Kentucky, but also #308 Long Beach St. Here's how Gonzaga's RPI rank would have looked with certain games removed from their schedule:
Loss vs. #1 Kentucky............43 (no change) Win vs. #308 Long Beach........38 (+5) Win vs. #232 Washington St.....40 (+3) Win vs. #161 Washington........43 (no change)
As the game against Kentucky indicates, losing to a highly ranked team doesn't help a bubble team's RPI much. So Gonzaga was not helped by losing to Kentucky, yet they did suffer for beating LBSU and WSU. The RPI is a mish-mash of results, where sometimes winning hurts (but you knew this). The thing is, almost everybody has games against weak teams on their schedule and feels this effect to some degree.
And this effect might not be so bad. One point to consider is this: how would you replace the stinker teams on the schedule? One way is to schedule a non-D1 team, a game that won't even exist is the eyes of the NCAA. Supposedly the committee frowns on such tactics, but to what degree who knows. The other option is to schedule a better team.
The problem is, the better the team you play, the more likely you are to lose, and a loss will certainly hurt your RPI. Gonzaga's loss to #82 San Diego had as much negative impact as their win against LBSU. Had they scheduled anyone worse than #82 and lost, the effect would have been worse than the win against LBSU. And the risk of losing to a team ranked 101-200 is twice that of playing someone ranked 201 or higher. Teams ranked 40-60 in the RPI - the bubble teams - were 130-13 (.909 win %) against teams ranked 201+ in the RPI, but they were 146-36 (.802) against teams 101-200.
So in exchange for playing a nearly risk-free game, why shouldn't a team be penalized? True, sometimes one can't anticipate just how bad a scheduled team will be in the upcoming year. But for the most part, I'd say a team knows when they're scheduling a win. And a few teams seem to do this better than others (I'm looking at you Georgetown, Virginia, and Pitt). A little incentive to avoid this practice isn't a bad thing.
There are some improvements that could be made to the formula to make it more fair to teams that can't help playing bad teams because of conference affiliation. Add margin of victory, or throw out the games against the 1 or 2 (or more) worst rated teams on the schedule. But any change would make a simple formula more complicated. The best thing the RPI has going for it is its simplicity. And unlike the BCS, the RPI is only a tool that humans use to make their own decisions, so whether Gonzaga finished 43rd or 38th wasn't a big deal.
Next week: The effect of not acknowledging home court advantage.