The woes of Block
In a discussion of tanking mechanics on the forums, Ghostcrawler made a long and in depth post about various subjects that helped consolidate one of the real problems with block and block value in Wrath of the Lich King. Not only is blocking something that only two of the four tanking classes do, but it's a pretty lackluster stat for boss tanking.
Block as a mechanic is somewhere between avoidance and mitigation. Ideally it removes a fair amount of damage (vs. all damage) reasonably often (vs. rarely). If block is up 100% of the time it just becomes armor that you improve through a different stat. We have let block chances creep up frankly because the amount blocked is pretty trivial when bosses are hitting for 40% of your health pool every swing. If this still strikes you as too RNG, imagine abilities like Shield Block and Holy Shield that could guarantee 100% chance to block for a short period of time.
We don't think block is cutting it as a mechanic, but the direction we are likely to take it is probably more of a change than you are considering.
The problem with block (which is really two mechanics in one, block rating which determines how often you block, and block value, which determines how much damage you subtract from a hit when you block it) is that for trash, it's inflated due to the block chance creeping upwards that GC mentions above. But for boss fights where a boss can either hit you physically for far, far more than you could ever block or hits you with massive magical damage that block does nothing at all against (well, unless you're a warrior in Tier 8 with the four piece set bonus) block has simply fallen behind the curve.
This is an issue because, as Ghostcrawler posted in another thread:
"We were starting to see many guilds ask their warrior or paladin to step aside so the DK could tank the hard mode encounters. This was not an isolated incident for a few guilds -- this was the kind of widespread phenomenon that really makes us take notice. If it was a boss or two that the DK was the best at, we would have just kept an eye on it. Increasingly though it was every hard mode. :( I will be the first to admit that the community is wrong sometimes. We don't think that is the case this time. The numbers backed up their conclusions pretty well. "
We think there is a risk that druids will take the place of DKs now. We think that risk is small because while druid armor and health are high, their cooldowns are nowhere near the DK level. So we'll just keep an eye on it for now.
Part of this comes from the dichotomy of Avoidance vs. Mitigation on tanking gear and how block currently fits into these mechanics. Avoidance (think Dodge or an increased Magic Resistance) is random and often all or nothing. You don't dodge half of an attack. High avoidance can lead to a situation where you take absolutely no damage for several swings and then take massive spikes of damage when it fails. Avoidance is certainly worth gearing for, but you don't want to put all your tanking eggs in that basket for fear of being the kind of tank who makes healers tear their hair out at how random and unpredictable damage is to you. Block Rating shares the random nature of an avoidance stat: you either block or you do not.
Mitigation, on the other hand, isn't random at all. High armor doesn't have the 'will I dodge or not' flavor, it simply always reduces how much incoming physical damage you actually take. As GC points out, mitigation is a great stat but it doesn't have the random factor that can sometimes save a tank's bacon. If you're down to 10k health and the next big swing is going to hit for 20k, avoidance might save you but mitigation certainly won't. Mitigation is a far more reliable stat which allows healers to have much more of a sense of how much damage a tank is going to take. Block Value shares the predictable nature of a mitigation stat: you know exactly how much you're going to block for. Of course, abilities like Shield Block and Holy Shield alter chance to block and in the case of SB how much you block for (so if you had 1200 SBV and hit shield block, you're now at 2400 SBV) which gives some wiggle room.
However, even with a cooldown ability, blocking usually simply isn't going to take enough damage off to keep a tank alive through two big hits from current 'boom damage' bosses. This is why blocking has become lackluster compared to other stats on gear and why DK's and Druids, with their much more predictable damage taken as tanks and higher health/armor pools, are prefered for hard modes over warriors and paladins. They're simply easier to heal. Blocking doesn't do much at all for situations like this. As long as blocking is so unimpressive, the tanks that don't bother to block will always be subject to incoming nerfs like this and balance between tanks will be difficult. It's therefore in every tank's interest if block can achieve parity.
What's the solution? Well, just allowing blocks to block magic damage doesn't really do much to address the big spikes of damage that block is failing to address as a mechanic. It's nice if blocking could prevent 20% of incoming magic damage, yes, but it still doesn't fix the oh snap he's going to hit me for 25k three times and the healers all have to move to avoid yet another burning circle of death and/or dismemberment on the floor so I have to take those three hits and somehow stay up mechanics that favor DK/Druid tanks. How do we make block relevant for those fights? Jacking up block value would possibly help to some degree, but then there's the use of block value as a threat stat to consider. If block values tripled, then Shield Slam damage would skyrocket as well. You know there would be problems if Shield of the Righteous started hitting for 10k and critting for 20. Also, if Block Value also blocked magic you run into the danger of PvP balance.
SInce GC has already mentioned that block rates have already gone up, a straightforward buffing of block rating probably isn't the answer either. They've already done that, and block still isn't cutting the mustard. In the end I'm forced to come back to the statement "the direction we are likely to take it is probably more of a change than you are considering." What does this mean? Obviously, I don't know, but it's possible that we could see the end of block value entirely and a shift to Block as a pure avoidance stat: you block, you take no damage. Then block rates could be dropped and Shield Slam/Damage Shield/Shield of the Righteous damage would be based entirely off of strength. That's one possible radical change that I can think of and I'm sure other tanks could think of others.
At any rate, block in its current state simply isn't nearly as compelling as it once was. It's moved from a solid all around tanking stat to more of a threat stat. Hopefully whatever they have planned will help with tanking parity and make the stat more useful.
