from Wikipedia. On August 2, 2012, the NCAA Division I Board of Directors approved a significant change to the process to determine bowl eligible teams, going so far as to potentially allow 5-7 teams to go to a bowl, in case there were not enough regular bowl-eligible teams to fill every game. If a bowl has one or more conferences/teams unable to meet their contractual commitments and there are no available bowl-eligible teams, the open spots can be filled – by the particular bowl's sponsoring agencies
Once every school with a .500 record or better is assigned a bowl they'll start going after 5-7 schools from the power conferences to fill the slots.