Actually on May 6th San Jose State and and May 4th Utah State accepted invitations to join the Mountain West. The two schools worked together for over a year to pull it off. IIRC the MWC wanted each school to have it's pwn press day, hence the two day difference.

Everyone knew this was coming. The Texas schools got to work on their options. UTSA joined CUSA in April as well. They got Board of Regents approval to accept an invitation on April 5th, news broke on April 28th, and they made it official. New reports already were mentioning the pending announcements of USU and SJSU to the MWC. LTU also joined CUSA officially on May 4th, 2012, and North Texas moved from the SBC to CUSA.

Everyone moved at once. It really was inevitable when the BYU project failed, the MWC preemptively inviting Fresno State and Nevada, then Hawaii (not sure I remember the exact order). At that point SJSU and USU started working with each other for MWC invites and Karl Benson planned his exit to the Sun Belt. Everyone else started looking out for #1 except NMSU (led at the time by the disastrous Barbara Couture) and Idaho.

When even your Commissioner bails out for another conference, you know things are bad