The post-season baseball tournament involves a field of 64 teams with 30 teams being awarded automatic bids for winning conference titles. Six of these automatic bids typically come from these baseball conferences: Pac-10, ACC, SEC, Big 12, Big West, and Conference USA. These teams are often 1 seeds. The remaining 24 automatic bids are typically 3 or 4 seeds.
If a team is not a conference champion, then they’re competing for the remaining 34 invited at-large spots. That’s where the RPI or Ratings Percentage Index comes into play. The most powerful conferences send multiple runner-ups at-large teams to the tournament. These at-large teams are typically high RPI ranked teams and are often slated at 2 or 3 seeds. One criticism of the NCAA selection system process is that the RPI rankings that they use in picking the at-large teams have been shown to favor SEC, ACC, and to a lesser extent Big 12 teams over Pac-10, Big West, and Conference USA teams located in the western US.
Taylor Starr (click to enlage)
The RPI formula is an algorithm made up of three main components:
1 – Winning percentage – makes up 25% contribution to the formula. If the winning percentage is 0.774 (24-7 record), then 0.774 x 0.25 = 0.194 or 25% of the total RPI.
2 – Opponent’s winning percentage – makes up 50% of the formula. Sometimes a team’s RPI can drop even when winning a game over a low RPI opponent because that opponent had a poor winning percentage. Conversely, the RPI can rise even when losing to an opponent with a high winning percentage. Playing a strong schedule is important for achieving a high RPI.
3 – Opponent’s, opponents winning percentage – this makes up the final 25% of the formula. The RPI for a particular team can move up with a win over an opponent that has played other teams with high winning percentages.
To calculate the RPI, the opponent’s and opponent’s opponents winning percentage or sometimes referred to as the strength of schedule is determined. In this example it is 0.536. Thus, 0.75 x 0.536 = 0.402. The RPI is then calculated as the sum of the winning percentage and the strength of schedule (0.194 + 0.402 = 0.596). Teams are ranked by the RPI values, and in this case the RPI ranking is 19 (18 teams with higher RPIs). A common mistake made by fans and members of the media is to refer to the RPI rankings as the RPI, though it is the rankings and not the indexed number that is important in comparing potential candidates for post-season play.
Boyd Nation’s and Warren Nolan’s RPI are very close approximations of the official RPI that the NCAA uses. In addition to the 3 components of the RPI listed above, there are some bonuses and penalties in the official formula for non-conference games, but neither Boyd Nation or Warren Nolan know the exact formula for these secret bonuses and penalties that the NCAA uses. Teams receive bonus points for beating top-75 RPI ranked nonconference opponents on the road, and penalty points for losing to bottom-75 RPI ranked nonconference opponents at home. Bonuses and penalties are on a sliding scale, separated into groups of 25, with the top bonus for a road win versus a 1-25 team and the worst penalty for a home loss to a bottom-25 opponent.
In inviting the 34-at large teams to the 64-team field in the post-season tournament, the selection committee uses the following criteria:
- Overall record
- Division 1 record
- Overall RPI Ranking (Teams with an RPI ranking of 45 or above have a chance at making the cut for an at-large selection if they are from a baseball power conference. Any team with an RPI ranking higher than 32 is virtually assured an invitation.)
- Non-conference record and RPI rank
- Conference regular-season record and conference tournament results
- Road record and RPI
- Last 15 games’ record
- Record against teams ranked 1-25, 26-50, 51-100, 101-150 and below 150 in the RPI
- Head-to-head record (record against other potential invitees to the tournament)
- Common opponents’ record (same as in #9)
As you can see, the RPI ranking is an important but controversial metric used in the tournament selection process and appears in 4 of the 10 criteria employed by the selection committee.
Changes ahead for the RPI
This will be the last year using the current RPI formula. The purpose of the change in 2013 is to reduce the road disadvantage faced by northern teams that must play a large part of their early season schedules on the road while southern teams play mainly at home. Starting next season, the RPI will be weighted for wins and losses, on the road and at home. A road win will now be worth 1.3 instead of 1.0 in determining the RPI rankings and a home win will be 0.7 instead of 1.0. Under this formula weighting, a home loss will count as 1.3 in reducing the RPI and a road loss will count as 0.7 in reducing the RPI. A neutral site game will count as 1.0 and will not be weighted.
RPI bonuses will be eliminated in 2013 as well.
