so important, suddenly, BYU becomes a huge elephant in the room. Other schools considered candidates for expansion by the Big 12 simply don't have BYU's track record of good teams over a long period of time. In other words, if increasing the conference's strength of schedule becomes a priority, BYU is the safest choice out there.
But with five conferences jockeying for four playoff spots, increasing your own conference's strength of schedule isn't the only thing to be concerned with - you don't want another conference to strengthen itself so that it passes you up and potentially steals a playoff spot. So maybe the Pac 12 bites the bullet and grabs BYU so that the Big 12 doesn't.