It's true that dps is very important. Another trick to this is that besides the dps focusing on the tanks, the MT can also inflict some damage using his abilities onto it for the agro won't drop from you normally during this "buffing period."

Here's another tidbit, most groups can definitely last one tank buff onto the boss, some well geared groups can take on two tank buffs, but do not let him get the 3rd. The 3rd will most likely wipe all groups unless it's on normaly mode and you MT and Healer are godly epic-ed out. I've done it for fun just to see how long I could last. Made it to 3rd buff before he smacked me for like 4k damage each time. I'm a feral druid with a 72% damage reduction, so you can tell he hits hard!!