I don't think this comes down to proof. There would be some legal wrangling if the Big12 goes after ESPNThe Big 12 will have to prove they broke the rules in court to get that money. Or at least threaten and posture enough to get Ou and UT to pay a good portion of it in a settlement. Depends on how good of proof we have
I don't think there is much argument if OU & UT leave the Big12 before the current contract is up, they are breaking the GOR. If UT & OU can get out of their GOR, then chaos will occur. ACC schools try to void their agreement with ESPN that runs through 2036. Even the AAC with has agreement with ESPN through 2032 could be challenged.