Then it's a failure on the tank for not outputting the max it can do. Reprisal, Arms Length, Rampart, 90 Second cooldown, short cooldown, leg kick, burn their damage off-gcds. If it goes South the other tactic is kiting the pull, kiting makes it very difficult for mobs to attack you because they have to all push each other trying to reach you, this can reduce damage more than Tenacity does since you'll be cutting off 50% of the mobs auto attacks.