Further details unveiled for RPI use in postseason
AURORA — The details of the RPI formula to be used in postseason qualification are starting to come into focus.
On Wednesday, the CHSAA staff formalized the outline to be used by all team sports committees as it pertains to the Rating Percentage Index (RPI) formula.
“The membership, for years, has been requesting a more transparent system that would provide more consistency among all sports and state qualifiers,” said CHSAA commissioner Paul Angelico. “We believe the RPI system, as it is set to be implemented, will accomplish this.”
Already, CHSAA’s Board of Directors has issued a policy mandating the use of an RPI for postseason qualification in all team sports beginning with the 2016-17 season in an effort to find more consistency across team sports. The heart of that RPI formula has already been announced, and it deals with a team’s winning percentage (WP), the winning percentage of a team’s opponents (OWP), and the winning percentage of the opponents of that team’s opponents (OOWP).
Specifically, the formula used will be:
RPI = (¼ × WP) + (½ × OWP) + (¼ × OOWP)
The biggest development from Wednesday is that all team sports, save for football, will not use a modifier for teams playing across classifications. This is because historical data examples run over many sports and multiple years have consistently shown that a classification modifier already exists within the formula.
On average, there is a 15 percent difference between the RPI of a team from one class to the next. For example, data has shown that the average RPI of a 4A team is 15 percent higher than that of a 3A team. This is also true when comparing a 3A team to a 2A team, and so on.
Moreover, all team sports, save for football, feature many mixed-classification leagues which are made necessary by geography. That is prohibitive when considering whether or not to use a modifier for classification within the RPI formula, as it consistently gave those teams competing up a classification a distinct advantage.
Football, as many know, is another animal altogether. It has seven total classifications, does not have near as many mixed-class leagues, and, perhaps more importantly, has far and away the fewest regular season games of any sport. And those factors are why it was deemed that a classification modifier is necessary in football. The modifier will be a 15 percent difference per class.
In addition, football teams competing down a classification will have a one-time exception allowing the first scheduled game against a team from a lower classification to count as the next-highest classification.
Other major details of the postseason process to be used by team sports committees:
- League champions will be protected and automatically qualify for the postseason.
- The remaining postseason qualifiers will be determined by the RPI rankings.
- Committees will set their own seeding criteria, but will start with the RPI as their primary consideration. Included in that is the option to simply seed their brackets according to the RPI.
- Suggested criteria the seeding committees can use, in no particular order:
- Geography
- A coaches’ poll, conducted by CHSAANow.com
- Head-to-head
- Common opponents
Further work remains to be done, but sport committee meetings begin in October. Things will begin to take a firm shape at that point, with only the final hurdle of the Legislative Council meetings next January and April remaining.
