When you normalize their viewership based on time slot and network, they're highly mediocre. They literally just posted the worst Rose Bowl ratings in history.
Any comparison to AZ/ASU, who are often relegated to the PAC network, is apples to oranges. Utah wouldn't have the kind of success they've had in the B12 (no wins against OOC P5 in 5 years), and success is cyclical anyway. Next year ASU could be better than Utah, get those nationally televised slots, and Utah's ratings would slide back to what they were in the late 2020s (downright bad).