We currently get 20% Stagger for being in tank stance, plus Mastery directly buffs it for a total of about 37% or so of Stagger mitigation at all times assuming you're in average tank gear.
Looks like in Legion we will have a base of 6% Stagger which we could talent for another 5% giving us a grand total of 11% Stagger at all times, if we get that talent...which is looking pretty shitty compared to the other two options.
Instead in Legion, they're going to give us Ironskin Brew to compensate which gives us 60% stagger for a few seconds, but it'll only be up for about half of the time or so, if that. It's basically our version of the Prot Warrior's Shield Block ability.
Also in Legion, instead of using Guard as a way to protect against spell damage, they are also letting Stagger mitigate magic at half the rate. So the 60% stagger buff will also give us 30% magical damage mitigation. Don't know how I feel about that, I guess it'll be better on some fights and worse on others.
What do you guys think of this change? Won't it hurt our sustained mitigation? Giving us more RNG like Ox healing Orb procs and RNG Dodge Mastery seems pretty shitty.