I've said it on the MWC board and I'll say it here. Air Force (outside of the other service academies) has a different goal than all the other schools. Their job is to train cadets to become officers, and sports are a way to do that. However, they suffer from attrition already in the MWC due to being smaller in size all-round. Going to the Big 12 would cause the attrition to be even higher, and their mission is not to send half-crippled officers into the armed forces.