Looks like they are using RPI so strength of schedule would play a big part.
RPI stands for “Ratings Percentage Index.” In short, it is a way to measure a team’s strength relative to other teams, based largely on the strength of their schedules. The RPI formula is used by both the NCAA and NAIA, along with many high school associations and among other organizations, as part of their postseason system. RPI is calculated from the team’s Winning Percentage (WP), the Opponent’s Winning Percentage (OWP) and the Opponents’ Opponents’ Winning Percentage (OOWP).