Tuesday, January 23, 2018
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Rating the Rating Systems

Photo courtesy of Andy Lyons, Getty Images.

As we turn the page on 2016 and the non-conference portion of the college basketball season, it’s time for bracketologists to turn up the heat.  Each week from now through Selection Sunday, March 12, BracketBluster will present an updated bracket plus some thoughts and interesting statistical nuggets of the college basketball season.   

Today BracketBluster will take a look at the most commonly used rating systems that writers from all over the country reference, KenPom, Sagarin, ESPN Basketball Power Index (BPI) and the Ratings Percentage Index (RPI).  To create a reference point for measurement, last year’s final rating from each of these systems will be compared to the final tournament bracket.  

KenPom and Sagarin seem to be the “go to” for writers which is interesting because they are the only two that contain a pre-season strength of schedule component based on historical data.  While it makes sense to basketball fans that an ACC team is generally better than a team from the SWAC or MEAC, using historical data to separate teams from power conferences seems random at best.  

The ESPN BPI does not contain any historical strength of schedule component.  They also do not release any data until after the first couple of weeks of conference play.  This allows the strength of schedule component to mature somewhat before releasing any data.  Similarly, the Ratings Percentage Index does not include a historical strength of schedule component though the NCAA does release this data periodically in the pre-conference season.  The RPI doesn’t gain the favor of writers as it does not pass the “eye test” since teams that schedule a tough pre-conference are overly rewarded, like UT-Arlington (10-3 overall and #17 in latest RPI) and teams that overload the schedule with Christmas cupcakes are penalized, like Indiana (10-2 overall and #99 in the RPI.)  

So let’s take a look at the 2016 data using a percentage variance from the baseline, pun somewhat intended:

BracketBluster 13.38%

RPI 13.54%

BPI 18.57%

Sagarin 22.33%

KenPom 24.61%

As much as writers don’t like it, the RPI comes closer to predicting the bracket than any other major rating systems except BracketBluster!  Check out our most recent anticipated bracket here. Following is ranking of all 351 Division I teams.