Everyone is suing everyone else.
As far as I knew, the MW set up a scheduling deal with the two remaining Pac-12 teams, but with a huge fine as part of deal if they invited any of their teams.
The Pac-12 is suing to not pay this fine along with the schools not paying their exit fees.
Talking with Pac-12 fans about it, they're actions are justified because the poaching fees were predatory.
Then they tried to invite HALF of the Pac-12 to join their conference.
So, clearly, the Pac-12 is justified in arguing that the deal they made restricts trade and they shouldn't have to pay these fines.
Any the MW got mad at BYU for leaving and having piece of work lawyers.