The seniority is going straight to arbitration, from what I understand the ATI MEC made a lot of promises to their pilot group concerning some issues in the contract and seniority, neither of which they had a right to do. In fact what I understand is JV withdrew some agreements that would have fixed some of the contract issues after Ace Ventura and his buddies wouldn't play ball. Kind of negotiation in good faith gone bad.
As for the seniority the ATI MEC knows they can't give what they promised so when an arbitrator rules they can go back to the pilot group and say it isn't their fault, they tried.