Why stay in a conference that is widely perceived as the weakest of the P5? Even if you believe that the PAC10 = Big12, why not move the needle to the Big12 by leaving the PAC, thereby making it the better conference and ensuring that you are in it? Why wait for UO/UW or more to leave and remove all leverage you might have? Also waiting is gambling that nothing is going to happen to the ACC and cause the Big12 to look east instead of west.
Seems like a no brainer to strike now.