"Why would you title the column this way?" you ask, as you reach for your "Please fire _______ from WoW Insider" form letter. "Crushing blows are out of the game, dipwad."
Well, yes. The crushing blow is technically out of the game, but another and worse mechanic has taken its place.
In this article I'm going to try to explain the source of "shield tank" frustration over health pools -- and why they are correct to see it as a problem -- and the Druid tank's unhappiness over the nerfing of Heart of the Wild -- and why Druids are also correct to see it as a problem.
Why the crushing blow was important
One of the biggest differences between pre-Wrath and Wrath tanking is the absence of the crushing blow. If you're unfamiliar with the term, then as a very simple explanation: any given raid boss had a 15% chance per melee hit to perform a 150% damage attack, which was also known as the crushing blow. It was typically a big damage spike and could lead to a wipe on progression content, with healers struggling to compensate in the small window of time before the boss' next attack landed. Burst damage is very unwelcome as it's often the greatest contributing factor to tank death. This is why reaching crit immunity is still so important to all tanks, and why the ability to avoid or absorb crushing blows was a fundamental part of pre-Wrath tanking mechanics.
The only means of avoiding a crush was pushing your dodge/parry/block over 102.4%, which would nullify the boss' higher weapon skill and render the tank immune to crushing blows. And this is how tanks dealt with that individually:
Warriors would use Shield Block to push their dodge/parry/block over 102.4%.
Paladins would use Holy Shield to push their dodge/parry/block over 102.4%.
Bears would eat it. Prayer was often involved as well.
Bears have no form of avoidance beyond dodge. Because crushing blows were the last attack to be pushed off a boss' hit table, a bear would need more than 85% dodge even to avoid some of them. While a gear set with >85% dodge was technically possible in late Burning Crusade content (and something similar was used by Rogues to tank bosses with predominately physical damage, which is why you saw all of those Rogue-tanking videos popping up in late BC), the amount of agility you needed to pull it off left you with a tiny health pool and almost no rage generation. You wouldn't get hit, but you also wouldn't be able to hold aggro, so it was the sort of catch-22 that made the situation an amusing one to consider, but then you'd laugh and go back to your regular tanking set.
Without the ability to avoid crushing blows, a Druid's armor and health had to guarantee that: a). the blow would hit for less, and: b). they would have the health pool to absorb multiple, even back-to-back crushing blows, because there was nothing the Druid or raid could do to change the boss' 15% chance to crush.
The Druid's overall damage taken was thus heavily reliant on RNG. You might go minutes or more on a raid boss without once being crushed -- and then there was the time on Teron Gorefiend where I was crushed on six successive attacks and we wiped. The only thing that could prevent that was better armor and more health, so Druids pushed their armor to reduce the damage, pushed their agility to avoid as many normal blows as possible, and then pushed their stamina to outlive the attacks.
The approach of Wrath and the new tanking paradigm
One of Blizzard's stated aims with the introduction of the Death Knight and the overhaul to existing tank specs was to address the chronic tank shortage on most realms. They did this by reworking the Protection Warrior tree extensively, introducing the ability to frontload threat and CC in the form of Shockwave, generate better reflective damage, and improving Thunder Clap to function as a relatively good form of burst AoE threat. Protection Paladins were altered to have better single-target threat and more controllable aggro generation, which somewhat addressed their relatively weak off-tanking capabilities. Bears overall were changed least in their basic threat mechanics, but were given occasional burst AoE threat in the form of Berserk, the removal of a target limit on Swipe, and cooldowns in the form of Barkskin in forms and Survival Instincts (a clone of Last Stand).
The net effect was to improve tank damage, soloing capacity, and threat scaling in an attempt to make tanks a little more user-friendly and fun to play. I would argue that in most respects Blizzard has accomplished that goal.
The Death Knight
Death Knights were also meant to allay the tanking shortage by providing a new, cool-looking, and predictably popular class that began life at level 55 and utilized several unique mechanics.
However, the introduction of a 2H-weapon tank who lacked the ability to block was a problem for the concept of the crushing blow. In the absence of block, Death Knights would be unable to become uncrushable without increasing their total avoidance from parry and/or dodge beyond 85%. Increasing their armor or health to the level of a Druid's would also have made them the single most powerful tank in the game against any form of damage, which was problematic for Blizzard's efforts to standardize tank quality. Developers were probably already concerned about the potential effects of Death Knight tanking talents on PvP balance. As we later saw, the Death Knight's impressive mitigation and avoidance cooldowns, coupled with frightening damage and self-healing, has made them an unwelcome and often resented opponent in battlegrounds and arena.
If you cannot change the class to suit the game mechanic, then the solution is to change the game mechanic to suit the class. Crushing blows can now be performed only by NPC's 4 levels or higher than a player character. As the highest-level NPC you will encounter in a 10- or 25-man raid is level 83, crushing blows functionally disappeared from the game.
The reappearance of the "crushing blow"
A crushing blow by any other name is still a "crushing blow" -- it's just not a crushing blow as we're accustomed to understanding it. When I say that the crushing blow has reappeared in the game, what I mean is that -- on encounters that matter, we continue to see enormous burst damage on tanks. The difference in new Wrath raid content (naturally we must exclude Naxxramas) is that the damage spike is typically magic in nature (e.g. Sartharion's Flame Breath, Malygos' Arcane Breath) which none of the three classic/BC-era tanks mitigates particularly well. Magic damage cannot be pushed off the boss' hit table and cannot be dodged, parried, blocked, or (for most raid bosses) interrupted or Spell Reflected.
Because the majority of your gear, talents, and abilities are completely useless versus this damage, the two things that matter most are your health (the more, the better) and your cooldowns (should you have them).
So what does each tank do about it?
Warriors eat it...which they are not designed to do.
Paladins eat it...which they are not designed to do.
Bears eat it, which is what we were designed to do when burst damage was nearly all physical in nature.
Death Knights use cooldowns to mitigate most of the damage, which is precisely what they are designed to do.
Why is this a problem?
Most of the time, it's not. In Wrath, the current raid content is sufficiently easy that any guild that works at it can usually clear everything given time. Sartharion's Flame Breath without drakes up is not particularly dangerous, for example. Blizzard is entirely correct in saying that you can clear all of the game's current content with any tanking class at the helm.
However, the current measure of a raiding guild is the degree to which they've made the content artificially harder by doing achievements. Your guild is no longer evaluated by the content you've cleared. Guilds and players don't advertise themselves by saying "MH/BT guild," or "3/6 Sunwell" anymore if they're after quality players. Hit the PTR around raid times for Ulduar bosses, and this is what you'll see in general chat:
"Twilight Vanq DPS LFG."
"Twilight Vanq/Nightfall Tank LFG."
"Immortal/Undying healer LFG."
This is how a smart player or guild will advertise themseves, both on the PTR and on the recruitment forums. If you want to compete with the best, it is no longer sufficient to advertise what content you're doing, because the greater accessibility of raid content renders it fairly irrelevant as an outward indication of player quality.
So what matters?
And the most important achievements overwhelmingly favor a Death Knight, or secondarily a Druid, tank.