I'm getting a lot of sidegrade quest rewards now, I need a way to identify decent gear without busting out a calculator. Can anyone roughly figure out this equation for time to live (for a warrior) against a 'typical' raid boss?
1% dodge/parry ~= X stamina ~= Y armor
That's what I'm most concerned with.
However, tankspot.com is not for entry-level nerds, so the larger equation would have shield block value, shield block rating, expertise, hit, etc. etc. etc.
I'm hardly at the point where I'm worried about expertise and hit, though.
Stamina doesn't suffer from diminishing returns. Additional HP are added on exactly like they were when you had 10,000 less of them.
Armor has ALWAYS had diminishing returns. Adding additional armor adds to your time-to-survive equally, but the effect of X additional armor is dependent on your current armor level.
Now dodge and parry (and "to be missed") have diminishing returns too. So while 1% dodge and parry still grant the same avoidance, no longer can you calculate parry and dodge percentage from a linear equation based on parry or dodge rating. The more parry or dodge that you have now, the less effect that each additional point of rating will yield in actual parry or dodge. (To make things more interesting, straight percentage additions from talents and racials don't have diminishing returns.)
Block has no diminishing returns, but its mitigation effects scale much more than they used to.
So at the end of the day, it's impossible to come up with a single equation referencing the dodge/parry/block/stam/armor/agi of an item and determining if it's better or worse than another item - for you! - without referencing your current stats.
Here's the rules of thumb you can probably go by at this point.
-Getting to 540 defense is vital for raid tanks (535 for heroics). More important than any other gearing decision.
-Once that's done, you'll want to keep a good balance of stamina and avoidance.
-Armor should not play much of a decision in your gearing options as a warrior, because items no longer have bonus armor; the armor they have is going to be largely reflective of the "item level", with items with higher level having more armor. This is actually good, as you can use it as a shorthand to determine which items had more points "spent" on them, which will generally be better point-for-point. But you can't use it as the sole proxy, because those items might have stats that are "spent" on stats you don't need (frost resist on non-frost resist fights!)
-If you have a choice between dodge or parry of roughly equivalent ratings, go for dodge. You should do this unless your dodge is significantly (10% or more) higher than your parry. That doesn't mean "never equip parry" - it's still an avoidance stat. But dodge's lower diminishing returns penalty means that it's a more-efficient avoidance stat.
-Block value is of limited utility. You also get block value with strength, in addition to additional AP, which will help you hold aggro, because your abilities (and threat!) mostly scales with AP now.
-Block rating is good stuff, though, because you won't constantly have shield block up. With block values up in the 1000 range even in full tanking gear, it's not insignificant for mitigation. That said, it's still not GREAT mitigation compared to the straight mitigation stats.
-Defense is pretty good even after you hit the cap. It's not like in BC, where adding additional defense after you hit uncrittable was a waste of item budget. It's not quite as good as dodge, unless you've got a lot of dodge; exactly how much depends on where "to be missed" diminishes to, a number which nobody knows exactly. Defense IS better than parry, so don't take off a defense trinket for a parry one! ;p (That said, if you're uncrittable, you may want to consider changing your gear load so that you gain more stamina; there's several crafted pieces with tons of stam and frost resist and a bunch of sockets, but no defense.)