Hmm, don't recall anyone bringing up the BYU issue yet, though its probably on an older thread somewhere ???.
BYU is not as good a school academically as Utah, but performs better on the football field (Utah has the stronger bb program). BYU has a better tv viewership, since they not only have their alumni, but a loyal Mormon viewership all over the west, particularly Idaho, Arizona, Nevada, California, and even western Oregon and Washington. :o
The downside is that last I heard, they do not do games on Sunday, and I remember reading something years ago that the Pac-10 would never consider a BYU thing until BYU got over that bit of fundamentalism. :-/
I remember some years ago also reading that BYU/Utah had an informal agreement that neither one would ever join another conference unless it was a package deal. Rivals should stay together. This makes sense, just like Arizona/ArizonaState years ago. :)
Anyone with better info please correct.. :)