The Pac deal is actually one of the newest where everything went to bid at the same time. I'd wager it is market for their ratings. They skimmed more inventory off for the PACN so that's about where they could go get more. Even selling 6 more conference games could add $2-4m per team to their contract.
B12's contract isn't bad, but it isn't good. It was able to keep it pretty even by going from 8 to 9 conference games when shit went south (conference games are worth several magnitudes more than non-con). The T2/3 deals are close to market as they were able to renegotiate them a few years back, but their T1 deal is very old and very under priced. The fact that they're still within swinging distance of the SEC is a pretty good sign. The Big Ten's massive jump had a lot to do with being able to get a new T1 deal, on a short contract (less risk, higher price) and add an additional conference game to the mix. The SEC could do this as well, by going to 9 conference games, but has chosen not to. Their deal with CBS is up in 2023, so expect that.
This is probably more of a topic for the realignment thread, but if they could add any P5 school and stay 9 conference games or more (the SEC is ten this year, I think we're going to see more of this than less in the future because they'll figure out it makes more money, even at the risk of less championships) they'll increase on par with everyone else. (E.g. Arkansas, Arizonas, etc) If they add someone who has even a shred of cache like Texas and Oklahoma, they'll become a power broker instead of just keeping pace. (E.g. USC or even Nebraska)
On a side note, and assuming all things stay healthy and don't shit the bed, the Big Ten gave a gift to the SEC this year. If the SEC was forced to go to ten conference games, in a packed P5, they'll be out of the lime light a bit as they'll have a lot more losses than their normal 8 game schedule. However, with two P5s gone, they not only will steal the narrative and get credit for that, but they'll also place more teams into the playoffs, with more loses, than if the Big Ten was playing.