But, this past season's TV ratings don't support your statements as Big 12 football had more eyeballs then the ACC. This was from a previous post and this includes FSU and Clemson so if Clemson and FSU left, the Big 12 would have far and away better TV ratings than the ACC.
Week 0/1: ACC: 11.002 million, Big 12: 9.443 million
Week 2: ACC: 4.642 million, Big 12: 6.138 million
Week 3: ACC: 4.137 million, Big 12: 4.166 million
Week 4: ACC: 5.311 million, Big 12: 9.035 million
Week 5: ACC: 4.781 million, Big 12: 8.174 million
Week 6: ACC: 5.831 million, Big 12: 4.821 million
Week 7: ACC: 2.580 million, Big 12: 4.642 million
Total viewers: Big 12: 48.857 million viewers, ACC: 38.284 million viewers.
This is a small sample size, but it clearly shows the Big 12 is holding it's own or doing better versus the ACC and the trends continued throughout the season.