This literally just happened to me.
I rouletted (yes, that's a verb) into Thousand Maws and straight off the bat the Healer says: "I can't cast Protect because I'm Level Synced D:" The Tank immediately drops and I explain (guessing because I'm not sure) that the Healer needs to reorder the Additional Skills so that Protect is further left.
We then had to disband because... well, what tank is going to Roulette into "Party in Progress"?
Personally, I think the Tank was a 1st class asshat. What do you think?