The problem is not DKs

You know, those encounter designers are right across the hall here. I am waving at them right now. We all work pretty closely together to match the boss abilities to class abilities. We work even closer together on the numbers. When someone is tuning Frozen Blows or Imbalancing Strike, they do that knowing what the stam pools, mitigation, avoidance and cooldowns are of appropriately geared tanks.

That's not to say boss design is irrelevant. Say for example we made a raid with one boss, like Eye of Eternity. Now say Feral druids were slightly better at that fight. Does that mean druids are overpowered for that encounter?

There are 14 Ulduar bosses. If DKs are better at tanking 5 of those does that mean DKs are overpowered? If the next tier of content has bosses that druids are better at tanking, does that make things equal?

We want them to all be close ideally. Since we don't want to give every tank the exact same stats and gear they are never going to be 100% equal. The trick is discovering how much of a delta is too much (and it's an answer that's hard to generate with math alone).

It's understandable that many of the tanking topics devolve into a "You're too good," vs. "No, I'm not," responses. Let's just try and keep it professional.

My original point was that we don't look at boss fights in terms of making sure that every tank class gets their moment to shine. That's not the goal.

We also don't look at the four tank classes and make sure they all have survivability within 1% of each other in all situations. That's not the goal either.

I felt the need to point that out to some of the players who may have unrealistic expectations. If certain classes have an easier time, we're totally cool with that, as long as the other classes are capable of doing it (and that includes the hard modes).

Now, if one class is too good at too many bosses, or we see guilds start to replace their MTs because another tank makes the fight so much easier, then that is something of which we take notice. I'm trying to frame it in those terms so that some player don't feel compelled to respond with "It's already happening in my guild," (because then the rest of the thread just becomes an unscientific tally of who uses what class for their MT) and other players respond with "Oh, great, QQ got us nerfed again."

Q u o t e:
Should we therefor assume that the degree of tuning in the initial release of Sunwell is gone forever, and that guilds who effectively play the game professionally should expect to have very little to do for months at a time?

Are you refering to the part where warrior tanks were kept alive by casting an anti-druid aura over the whole raid? Or the part where you stacked shamans for Chain Heal and Heroism rotations? Or where the mages were bumped to make room for more warlocks to benefit from Curse of Shadows? Or where paladins were parked outside to buff everyone in between wipes? :)

Players who liked Sunwell generally liked it because it was hard, not because the class balance was so exceptional. Mimiron's big red button is hard if that's your thing. Algalon is hard.

A lot of the tank balance problems we are having exist because we thought block would be a better mitigation stat than it has turned out to be. I say "we" because the druids and DKs were also convinced at the time that they would be mana-sponges and everyone was quoting "The unblocked hit is the new crushing blow."

For a variety of reasons, reality didn't work out that way. For one, we underestimated how much removing crushing blows would change the landscape. In fact, you can argue that the big magic hits (the dragon breaths and plasma blasts) are really the new crushing blows, and block does nothing to them (modulo 4 piece bonuses and the like). DKs were given amazing cooldowns, high armor and high avoidance to make up for them not being able to block. Druids were given even higher armor and high health. We backed druids off from that a little in part because they were going to end up with dps stats almost no matter what gear they chose so we wanted to incorporate those a little more into tanking. We kept buffing DKs based on early (mostly heroic dungeon) reports that healers hated healing DKs because they were so squishy when their cooldowns were blown. That seems to be less of an issue now with current levels of gear and some of the other changes to the game since then.

We will almost certainly change block. I can't tell you when we'll change it, because it's a big change. We probably don't want shield-users to be at 100% up time of block if they block more per hit. We have to be careful what happens to threat since that's a big part of block, especially for warriors. Heck, maybe we fall in love with the 4 piece warrior bonus and decide to make that a core part of the ability.

We might very well nerf DK mitigation or cooldowns again. We're less worried about druids, but if we nerfed DKs it might be that druids take their place. We are less likely to just buff the shield-using tanks because we like the current difficulty of the hardmode fights for them and we are reluctant to have to buff those encounters to correspond for a tank buff. Though as we've said elsewhere, we might give paladins another cooldown.

Just remember that one player's "slight advantage" is another's "faceroll tanking and trivializing encounters." The balance goal has always been "close enough" not "identical."