would be a better comparison. There are still a ton of factors that play into this such as network, opponent, time slot, team record at time of game, etc. I mean Wazzu vs Washington outdrew Utah vs Washington. I'm guessing the common factor there was Washington, for example.
Last season Utah only had 1 Nielsen-rated game against a current conference opponent, Baylor and it was on ESPN with about 1.3M viewers. BYU averaged 1.2M viewers over 7 games that fall into that category and 1 of those games was on FS1 which is a terrible draw compared to ESPN or the 4 main networks.
Looking at just the numbers with no context is almost worthless.