CU was a drain on the Big12 and the Big12 wanted to dump CU.
When Texas/OU made the announcement CU was the first school to apply to the PAC 10. PAC10 accepted them thinking Texas/OU were still coming....
CU didn't leave the Big12 due to Texas but not wanting to be left behind in a dying league w/o Texas/OU and others.
Go Cougars!!!!