If you read some recent developer comments about the game, you find out some strange things. It seems that it is impossible to heal through bosses with priests and shamans since paladin and druids AoE heals are so much more powerful. It seems that until recently most tanks were getting two-shotted because bears were so ridiculously tough that when the bosses hit hard enough to threaten bears, they hit way too hard for the other tanks.
What's interesting to me about this is that they balanced the bosses this way. They balanced the bosses around the broken tank and the broken healers. How could this possibly happen without simultaneously noticing that the tank and healers in question were dramatically overpowered?
Obviously at this point they have noticed the problems and they are figuring out how they are going to fix them. Despite that, I worry that the developers do too much of their balancing by tweaking numbers up and down based on experience and not enough of it based on math. There is definitely room for both things - no matter how good you are at creating models of situations, boss fights are extremely complex. Models and math can only get you so far and you have to dive in at some point and see how it works and whether it can be beaten with real raids. But some rudimentary math well before you got to the point would give you things like maximum theoretical healer AoE throughput and how long they can afford to keep that up in level 359 gear. It can give you things like the health of a bear tank versus a warrior tank, the size of Savage Defense shields and the frequency that the bear puts them up.