Big 12 uses total losses and then head-to-head in an unbalanced scenario. We'd go over Ok St.
https://big12sports.com/news/2008/7/31/1546006.aspxUnbalanced Tie-Break Procedures to Determine Conference Championship Game Participants In order for teams to be considered in a tie-break scenario to compete in the Big 12 Football Championship Game, teams must play no less than one fewer conference games than the average number of conference games played by all conference teams (rounded up/down at .50). For example, if the average number of conference games played in the 2020 season is 8.25 (value of 8 when rounded down) a team would be eligible to play in the Championship Game if that team played 7 conference games. The Championship Game participants will be determined by the best winning percentages within the conference. In the event of an unbalanced schedule where there is a tie for the best, or second best, record in the loss column, head-to-head results will take precedence over winning percentage as long as the required number of conference games were completed. If the teams remain tied, the following procedures will be applied to determine the Big 12 Championship Game representatives: