This is from a recent DNews article: https://www.deseretnews.com/article/865693183/The-rise-and-fall-An-inside-look-at-the-decline-of-BYUs-marquee-sports-programs.html

"During meetings with Pac-10 athletic directors, Fehlberg says they all told him the same thing — it was a no-brainer; BYU put more fans in seats on the road than any other school, even most of their rivals.

“I spent a lot of time working under cover of darkness to get us in the Pac-10,” Fehlberg says. “It was a done deal, but it didn’t happen.”

The Pac-10 told Fehlberg that BYU would need a travel partner. Fehlberg suggested Utah, but the idea was dismissed immediately — BYU already brought the Utah TV market to the league. Fehlberg approached Colorado, which immediately liked the idea of joining the league. But, as Fehlberg tells it, Colorado later reneged. He says CU officials told him that Texas governor Ann Richards threatened to sue if Colorado left the Big 12, which included many Texas schools.

That left BYU without a travel partner. According to Fehlberg, BYU’s move to the Pac-10 was put on hold. In the following years, two events occurred: Utah had two extraordinary, undefeated years in football and Proposition 8 went on the California ballot. “The entire equation changed,” says Fehlberg."