Probably figured playing in the Mountain West they'd never get a legit shot at a BCS title.
Boise State has got to be thinking, WTF. We leave the WAC to join a better MW conference, then Utah and now likely TCU leave. I wonder how long before Boise State joins another conference, either the Big East or Big 12?
It is just a matter of time before the Big East goes to 12 teams so they can have a championship game.
I've got to think the Big 12 will add teams to replace Nebraska and Colorado as well. They want the $$$ so they can continue to have a conference championship game.

http://msn.foxsports.com/collegefootball/story/tcu-expected-to-join-big-east-for-all-sports-112910