but mastery does provide a less spikey intake.
heroic garrosh you swap every 20-25
Heroic Garrosh is often solo-tanked, this point is largely moot. Even with 100% uptime on shield block, avoidance rating reduces twice the damage at 82% of the probability.
Probability of damage reduction does not necessarily mean you have an easier tank to heal. Taking the example to the extreme, 100% uptime on 1% damage reduction is not easier to heal than 90% uptime on 90% damage reduction.
A large reason that people tend to think mastery reduces spikes better than avoidance is a mis-representation of the piece-wise nature of warrior tanking.
In the simulations you'll often see people look at spike reduction over a certain number of swings
What follows are the worst case scenerios for 8 swing melees.
Even naked you are taking only 77.5% of possible incoming damage (hooray shield block)
But your actual worst case is Case 2:
85% of incoming.
So when people look at the effects of mastery on those streaks, even converting one block to a critical block pulls you below the 75% spike range.
However, that same rating budget, applied to avoidance instead of mastery, will take the 85% spike below a 70% spike more frequently than the mastery budget would take it to 75.
When you look at the smallest streaks avoidance much better at reducing the spikes (Even in bis gear, garrosh can still 2 shot you), and any streaks looked at above six are largely useless due to the cyclical nature of warrior tanking. This seems to always be overlooked when people are analyzing the spikiness of a tank.
Edited by Booi, 23 June 2014 - 10:42 PM.