Washington was 4-4...they were also competing against LSU/Bama and a Michigan game.
7-3 and #23 ranked Utah should be a bigger pull (especially considering that they were only competing against one ranked team in their time slot, playing a team with a losing record; which is one reason why Oregon/Utah got the network/time slot). I'm not dissing on Utah here. I'm just saying it's tough to just grab one data point (viewership) and claim that Utah is a bigger pull than other West Coast teams.
The Oregon-Utah game SHOULD have pulled large numbers and it did. The 7:30pm ET ABC game should be the #1 game of the week unless Bama/Ohio State are playing a ranked opponent on CBS/ABC that day...which is exactly what happened this week (and Utah-Oregon was #3 even though it was in what is generally the #1 slot). Again, not a knock at Utah; nobody is competing with those two games.
Sic'Em 365 had a nice article today that broke down timeslot and network for a longer period of time (but it's 2013-2019).