Crimson's gear evaluation system
First of all, the following all assumes that the Warrior tank has all relevant talents, such as Shield Mastery, Toughness, Vitality, Kings buff, etc.
Everything is calculated based on the stats shown on the item. If you dont have the relevant talent, you have to reduce the values for those stats.
When evaluating tanking gear I judge it based on three things:
1) Effective Health. I convert Armor and Block Value into its stamina equivalent contribution to effective health. For a wide range of gear levels, roughly 15 armor is equal to 1 stamina, and 4.5 Block value equals 1 stamina (on items, before multiplying by 1.3). The reason block value counts is because against a boss you will block 2 hits on the way down, so each 1 final block value is worth 2 hp.
So I count up Effective Health stats on the item, Stamina = 1, each 15 Armor = 1, Block Value = .22
I call this value 'S' (short for stamina, which everything is converted into).
I use this as my primary determinant on gear for bosses or single mob trash pulls that are difficult to survive.
2) Threat Generation.
I went through and calculated what %age various stats would add to my threat generation, for reasonable gear levels (Kings Defender as weapon), a rotation of: Shield Slam/Revenge/Devastate/Devastate once 5 sunders are up, and heroic strikes for 2 of every 3 autoattacks.
I convert everything into 'O', for offense, which is equivalent to the gain from 1 hit rating.
I came up with:
Hit rating = 1
Weapon Skill = 1* (This is an estimate, I was unable to figure out for sure exactly what this does, but it seems about as good as hit rating, and there isnt much of it on items).
Strength = .55
Block Value = .5 (On items / before shield mastery)
Crit Rating = .5
Haste Rating = .5
Agility = .33
AP = .23
Parry Rating = .1
+1 Weapon DPS = 3.2
Proving these requires tons of math, and some stuff is estimations, but its at least close to this.
I use this as my primary determinant for threat sensitive fights (without sacrificing the others much)
3) Damage Prevention.
This is from both reliable (Armor/Block Value) and unreliable (Defense/Dodge/Parry) means. This represents the reduction in average incoming damage.
I use this as my primary determinant for multimob trash pulls, and 5 mans, in cases where I have only 1 healer.
I call this value 'D' for Defense. The baseline is 1 Defense rating.
This assumes that I am already uncrittable.
1 Defense rating = 1
1 Dodge rating = 1 (yes, theyre essentially equal).
1 Parry Rating = .9
1 Agility = .66
1 Block Value = .5 (on items, before shield mastery).
1 Block Rating = .4 (for its value on trash pulls with high block value. On bosses obviously its worthless, but this stat isnt my concern for bosses).
30 Armor = 1
This system ends up giving an appropriately high value to armor by double counting it in both the S and D categories, and to block value by triple counting it in all three categories. This is appropriate because those stats help in all of those areas. (i.e. the contribution to effective health given by armor is better than that given by stamina, because it prevents damage instead of requiring healing).
Some stats such as agility and parry give both defense and some offense, and thus are counted in each.
For example, lets compare Devilshark Cape and Farstrider Defender's Cloak using this system:
Here are the differences:
20 Def more than Farstrider (20D)
18 Dodge more than Farstrider (18D)
189 more armor than Devilshark (12.5 S/6.3D)
8 Stam (8S)
9 Block Value more than Devilshark (2S/4.5D/4.5O)
Farstrider has +22.5S, +4.5O, -27.2D vs Devilshark.
Its better for effective health and a bit better for threat generation, but much worse at damage prevention. Overall, an upgrade for boss fights if it doesnt lower your defense too much, and not as good on multimob trash.
This system is very useful to me as a way to (fairly quickly) estimate the relative value of two items.
My favorite thing about this is that it doesnt JUST evaluate effective health. It also tells me how much damage prevention I am giving up when I make item swaps that increase my effective health, because I dont want to get TOO crazy and completely ignore avoidance altogether. Currently I'm at about 15900 hp, 17000 armor unbuffed with about 45% miss+dodge+parry vs a lv 70 mob. I like to keep my avoidance (miss/dodge/parry) near 45% vs a 70 mob, at around that level I dont find that I dodge too much or too little.