Reasoning is pretty simple. I weight recent on-field performance pretty low. Instead, I weight school academic rating, historic sports performance across all programs, and natural TV market (population of surrounding area) as the highest 3. If I'm looking at that list of schools independently of who else may or may not join, i have them listed how I would value them.
1 - Stanford: unparalleled academic rating, great historic athletic success, massive TV market in the SF Bay Area (~7.7 million)
2 - Washington: strong academic rating, athletic success has been middling, large TV market in the Seattle Area (~4 million)
3 - Colorado: similar profile to Washington with pretty good academics, ok athletics, and large TV market in the Denver area ( ~3 million)
4 - Here is where i would have Oregon. Academic rating on par with Colorado, athletic success much greater than Washington or Colorado, but TV market also much smaller.
If I'm forced to take Cal along with Stanford to capture the SF market, then they move way up on my list. Utah again fits ok in the academic wing, but offers very little in historic athletic success. Some recent success, and SLC while a pretty large TV market, isn't huge and is mostly dominated by BYU anyhow. For those reasons, the Utes are last among the 6.
They would, however, be a very attractive option for the B12 since BYU is joining in with them. The AZ schools also would be good proximity fits for the B12. Oregon would probably be best suited for the B1G, especially if Washington is added. If not, then a PNW wing of the B12 with both oregon and washington schools might work.