What is RPI in Softball?

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What is RPI in Softball?

RPI is an acronym that stands for Rating Percentage Index. This index was created in the late seventies as a tool to rank teams based on their wins and losses, and it isn’t exclusive to just softball. The RPI is used in multiple sports, including NCAA basketball, hockey, baseball, lacrosse, volleyball, and soccer.

This ranking system is a tool that’s used in the selection and seeding of teams that will go on to face each other in the playoffs. There are a few different polls that rank Division I softball teams. There’s the ESPN/USA Softball poll, the USA Today/NFCA Coaches Poll, and a Women’s Softball RPI.

The current formulation of the RPI is made up of a team’s winning percentage (25%), the winning percentage of that team’s opponents (50%), and the winning percentage of this opposing team’s opponents (25%). These percentages are also known as “division I winning percentage,” “strength of schedule,” and “opponents’ strength of schedule,” respectively.

How important is the RPI?

According to the The National Collegiate Athletic Association (NCAA), “The RPI is just one of many factors used by the committee. Each committee member must weigh each factor available and make his or her own decision regarding its importance. Clearly, the RPI will be more helpful to a committee member when evaluating a team out of out his/her region, especially if he/ she has never seen them play. If a committee member is evaluating two or more teams, a wide difference in RPI rank can be a factor. How “wide” is “wide”? A good rule of thumb is 20 or more ranking places, as well as the actual mathematical difference between RPI rankings.”

One issue with the RPI is that it lacks a certain statistical justification, as it does not include more intricate, important details such as the margin of victory for the games a team has played. Including other statistics like these would serve as a more accurate predictor of the outcome of a game between two teams listed on the index. However, the purpose of not including statistics like the margin of victory is that these stats have a history of being manipulated by teams or players who have accepted bribes, and then modify their gameplay so that the resulting victory margins better suit their bribers, who have gambled  money on the game. (This is a fairly complicated form of gameplay manipulation known as “point shaving.”)

Here’s an FAQ for the RPI as answered by the NCAA:

Some of the conference rankings really seem out of whack. How can the RPI rankings be so different from the perceptions some have of the various leagues?

“The key thing to remember about league RPIs is every team has an equal impact on the conference ranking. A league with three or four outstanding teams can end up ranked in the middle of the pack if the same league also has three or four very poor teams. The teams essentially cancel out each other. Thus, a conference with few top 20 RPI teams, but also none below 150, can have a higher league ranking than a conference with more top teams but also a few 150-200 schools. Those who offer opinions about which are the top conferences tend to compare the top four or five teams with the top four or five of other leagues. There is nothing wrong with this type of evaluation, just as there is nothing wrong with a mathematical evaluation that takes into account all teams in one league. The factors that determine the “best” league always will vary depending upon who does the evaluating, and what region of the country they are from.” – Answer provided by the NCAA.

What is the best way to improve a team or conference RPI?

“The simple, but correct answer to this common question is schedule and beat non-conference teams ranked higher in the RPI. But playing a tough non-league schedule only helps if the team or league wins most of those games. The best conference plan is to have the coaches honestly evaluate their team, then schedule teams in a higher-ranked conference against which they think their team has a realistic chance of winning…this does not necessarily mean playing just top teams in a particular league. The weaker teams should try to schedule the weaker teams in the stronger league. The catch to this plan is that most leagues already try to schedule this way, thus making it more difficult for weaker leagues to find games against stronger teams. It also almost always means playing the stronger team on their court. Playing tough opponents at neutral sites, such as early-season tournaments, also can help.” – Answer provided by the NCAA.

Is it better for a conference to play more or fewer league games than non-conference contests?

“It depends on the conference’s ability to schedule strong, non-conference opponents and the overall strength of the league. A strong conference, with an across-the-board commitment to playing solid, nonconference opponents, usually is better off playing more league games, taking advantage of its’ teams expected out-of-league record. A weaker league has a better chance of improving its’ RPI by playing fewer league games and more non-conference, IF there is a total commitment by all teams to upgrade every non-conference schedule. Every league must carefully analyze what non-conference teams will be added by decreasing conference games, or dropped by increasing league games before making this decision.”- Answer provided by the NCAA.

Can the current RPI formula cause a “regional bias” in the team or conference rankings?

“Because of location, many conferences only play a small percentage of other leagues in their nonconference schedule. If the number of potential teams is small, the possibility that these teams will “beat up each other” could mean there would be fewer outstanding records to catch the committee’s eye, resulting in less at-large selections for teams in that part of the country. Mathematically, it certainly can be argued that with fewer teams available it is possible all the teams in that region could “bunch up” with similar records. Those in other parts of the country, however, could argue that if the great majority of these teams are strong clubs, it also reduces the opportunity to play very weak teams that hurt the strength of schedule element of the RPI. If the committee is asked to look past BOTH a team’s Division I won-lost record AND its’ strength of schedule, what other factors should it then consider? By eliminating or reducing the impact of these two factors on selection, elements like perception or reputation may play a larger role in the process. While that might benefit the traditional powers, it would make it more difficult for emerging teams to be considered, even those in that particular region. Should different parts of the country be considered for selection using different criteria? During its deliberations, the committee frequently has discussed scheduling limitations for many parts of the country and always has factored that into the decision process.”- Answer provided by the NCAA.

SOFTBALL AMERICA RPI:

ESPN.COM/USA SOFTBALL RPI:

USA TODAY/NFCA COACHES Softball RPI:

NCAA Women’s Softball RPI: