Previously, the selections for the FCS playoffs have been based on a school's Division I win/loss record and the subjective opinions of an NCAA committee. Now, with a field of 24 teams in the playoffs going forward, the FCS will be using a simple rating system to account for strength of schedule and to help identify teams that deserve a spot -- similar to how RPI is used in men's basketball. Lehigh Football Nation does a good job of explaining the change.