Like you said, it's all about matchups. When Utah played Ohio State last year, it was an intriguing matchup. First time Rose Bowl appearance for Utah, Urban Meyer ties to each school, two high-powered offenses, etc. It was an interesting matchup that appealed to B1G fans.

This time around, not so much. Utah wanted to avenge a loss and Penn State wanted another Rose Bowl W (achievable against a 4-loss team). Just business. The hype that fueled last year's viewership died down this year. Compare this year's game to a previous Rose Bowl game that also featured Penn State:

"While this year’s game aired on January 2 rather than January 1, that has not typically been a major drag on the numbers. The previous January 2 Rose Bowl in 2017 — USC-Penn State — averaged 15.74 million viewers, actually up from the previous year (the aforementioned Stanford-Iowa game)." - https://www.sportsmediawatch.com/2023/01/rose-bowl-ratings-record-low-viewership-cotton-gator-high-notre-dame/

To say that it is just a Jan 2nd thing is a fallacy. It really is a matchup thing. It also didn't help that Rising went down and Penn State put away the game in the second half. Using this sample size of 2 (I know it's small but it's what we got), one thing for sure though is that the B1G really drives the numbers. Evidence of this is our new media deal and future conference mates.

Averaging 10.2 million viewers is nothing to scoff at, but it is now the lowest viewed Rose Bowl to date. Matchups matter and I do wish more people saw the Nittany Lions win.