For Big 12 reference in the CFP rankings:
BYU went 1-1 vs top 25 with a loss to a non-bowl P5
ISU went 0-0 vs top 25 with a loss to a non-bowl P5 and a loss to an 8 win P5
Colorado went 0-0 vs top 25 with a loss to a non-bowl P5, a loss to an 8 win P5, and a loss to a 6 win P5
Arizona State went 1-0 vs top 25 with a loss to a non-bowl P5 and a loss to an 8 win P5
To that end, the Big 12 seems to have really suffered under (2) (limited ranked wins) and (3) (losses to non-bowl teams - Kansas and Cincinnati). Given no four loss teams made the rankings, it was fair to exclude the four loss Big 12 teams - KSU, TT, BU, and TCU - and that exclusion really hurt the resumes of the top 4 in the league since there were ultimately only 2 games against the top 25 teams among them (BYU vs SMU and BYU vs ASU). Parity seems to have been a contributing factor.