Same thing on toc 10 first boss, i was with my war tank (37k hp, 26k armor, 557 def, 30% on dodge,.....). My mate was a protladin (barely same stats), everytime i took aggro, i got nuke, (- 25 -30k on my face) when the protladin took 15k max. I was like "uh???????? wtf?", in my memory i never took this kind of damage.
Same on the dungeon whit the flying boss, utgrade or something like that when he bs my life disapear.
This is weird because i did ony 10, really pièce of cake. I lose12k hp max.
There is something wrong with some boss. Idk what but war was not weak like that. War tank was one of the most use, with protladin., on wotlk retail.