You probably haven't had him use Rake with a crapton of stacks on him, then. It'll all but one-shot most tanks. Our first time through, he chunked me for about 6k damage on an i102 PLD. Tanks really shouldn't pick up these adds. Heal/DPS should be dragging them into a corner and killing them asap. Personally, I grab this boss and take him immediately to the far corner to give them the largest amount of room possible to keep stacks off the boss.
Four DPS pancakes and a heal pancake on the side? >.<