The Big 12 made better decisions re: monetization than the PAC a decade ago. The Big 12 parked inventory on FS1 and got paid for it. The PAC parked similar inventory on the PACN and didn't make any money from it. So the Big 12 ended up making money on a bunch of games for which the PAC was making nothing w/ similar games. That accounts for a lot of the difference between the two conferences. Going forward though, you compare apples to apples, and the Big 12 has been pulling better TV numbers than the PAC for the last decade despite having a larger percentage of its games rated. Think about that. Even with the worst games included into the Big 12 average, and not included into the PAC average, the Big 12 is still beating the PAC.
I'm not convinced that the status quo gap between the Big 12 and the ACC is only 10% in viewership. BC, Duke, WF, Cuse, Pitt, and GT would all have bottom rung fan support in the Big 12. Like the PAC, the ACC inflates its average TV ratings by only putting about half of it on a national network to be rated. The Big 12 consistently put nearly all of its inventory on a national platform and was still beating the ACC in average TV numbers for most of the last decade. The last couple of years, with a thumb on the scale, the ACC has been only edging out the Big 12.
The Big 12 makes 3rd place money right now b/c it's TV ratings are in 3rd place. I'm arguing that the Big 12 - going forward - will be in 5th place and that its TV ratings will be in 5th place. However, the gap between the IR8 and the PAC/ACC, when it comes to TV, is not all that wide. Fans in the center of the country care more and they watch more. There's reason to think the money will therefore not be that far behind. There are going to be a lot of weekends when the IR8's best game is better than the best game being played in the PAC or ACC that same weekend. We occasionally had weekends like that with the American over the last few years.
The Big 12's media rights partners declined to negotiate b/c they had bigger fish to fry first (pro sports deals, the B1G, an expanded CFP, etc.) Disney may have also known something about what was coming with Oklahoma and Texas, too.