They just abused the OP comp right now Scholar + Drk 40% healing down stacked on a target you dont need to sleep the enemy healer or stun the kill target if your on tank, making you able to use stun as a pure defensive tool wich their tank did.

Healing down is way to strong right now i can totally see them fixing it for the next patch.
I think end of Stormblood with the FRC 2018 was the most balanced this PVP has ever been , but even then it was far from perfect.