While I agree that the OU/Ohio St. game will have much more fans there as a whole (and better weather it looks like) aswell as a larger national presence, the difference however is (2) Top 10 teams (#2 vs #10) playing eachother rather than a #3 vs #14. The performance of Lamar Jackson (even against lesser competition; but every team every year plays similar compeititon and hasn't done what he has) also has a lot to do with it too. He is a human highlight reel and ESPN is going to try and capitalize on that.
The ACC is also becoming ESPN's darling now that ACC Network deal is finalized and the SEC has looked mediocre so far.