We played them yearly from 1948-1958 after leaving to the Big 7. We skipped 2 seasons, but scheduled a home and home starting in 1961 where they beat us in an otherwise undefeated regular season. We played them in the 2nd half of the home and home in 1962 and then took a 50 year hiatus until we both joined the Pac-12 where they mostly kicked our ass for a decade plus.Yeah, I think a couple things got in the way - first of all being the long layoff. I don't think there were any Texas-Texas A&M style hard feelings over CU's departure, the rivalry continued for about 15 years after CU went to the Big 7, but then it just stopped for 50 years. The second big reason is that BYU actually made the Holy War a rivalry. I mentioned during that game that if you take out the Lavell Edwards years, Utah/BYU is more lopsided than CU/CSU, but since Edwards was able to close the gap, BYU became a true rival for Utah.
I thought at the time that CU/Utah had the potential to become a good rivalry, especially because BYU and Utah became estranged and weren't going to play one another, and it started out well, with us winning the first game in the Pac and keeping Utah out of of the CCG, but what kind of rivalry is it when one team beats the **** out of the other every single year.
It sucks because with the Nub rivalry dormant, CSU back to becoming nothing close to a rivalry, and BYU and Utah back together again, I feel like we're cast adrift in rivalry land.
The only real scenario I can see the rivalry staying is if they'd joined the Big 7/8 alongside us.