Nothing too surprising about the fact that day games on network TV are the highest rated. Only marginally surprising that UW was in 5 of the 10 top games (they are a marquee program), but that also could be a result of them having more network/day games than other teams.
4 of those top 10 games are likely more about the non-conference opponent than the Pac12 team (see: USC/Notre Dame, Washington/Auburn, Oregon State/Ohio State, Stanford/Notre Dame)
I find it interesting that the Colorado/Nebraska game made the top 10 (although, again, a day game on network TV may be all the explanation needed). It is a traditional rivalry, but would not expect it to get much attention beyond the regional level, so maybe the simplest explanation (day game on network tv) is the primary reason.
Obviously games on Pac12 network will not get as many eyeballs, nor will night games, but the rebuttal is that if you do not put compelling games in those slots, you won’t get $$ for them. Tough balancing act.