that is exactly correct, at least if blizzard implemented the same level of DR as they did to armor anyways.
Was replying to a thread on the WoW tanking forums. And got me thinking. Maybe some of the number crunchers can figure this out better than I, and tell me if I'm way off base here.
Was seeing many people ask what gems to place in their gear. How much Dodge or Parry is too much. At what point does it become useless to get more Dodge rating. Etc, etc.
This is just a copy/paste of what I posted on the WoW forums.
I'm not sure if the math is even close to right on this - but at least this is how I see it in my head...
Now in the game we have al these ratings that are effected by diminshing returns. They diminish in effectiveness the higher your rating is. Even though Armor does not have a "rating" associtated with it, if you think of it that way, it becomes easier to see the relationship between it and Dodge or Parry.
At level 70, 10,000 armor (rating) reduces incoming physical damage by 48.644%. Increase your armor (rating) two fold - to 20,000 only yields a 65.45% physical damage reduction, due to diminishing returns. Your overall "time to live" (as some like to call it) has actually doubled, as it will take twice as many hits to kill you.
I am using this line of thinking when I compare Dodge/Parry to Armor/Stamina. If I increase my Dodge rating from 100 to 200, that would be the same gain as going from 1000 Armor to 2000 armor - regardless of what the percentages on my character sheet reflect.
Failure is not an option. It comes bundled with the software.
You and Kaze have it just right. That is to say, if the budget for x armor on an item (where x is the amount of armor that increases your "time to live" by exactly 1%) is the same as the budget for y dodge on an item (where y is the amount of dodge that increases your "time to live" by exactly 1%), then x armor and y dodge would be equally desirable b/c they cost the same amount and yield the same benefits. Keep in mind that this is an analysis in a vacuum, and doesn't consider the relative importance of EH and avoidance other than how they increase your "time to live" in abstraction (see every post ever about EH vs. avoidance for more info).
Also, there's no DR on stamina. :P
I agree, there should be a way to directly compare the survival value of mitigation with avoidance now, but here's the tricky part:
Parry and Dodge are diminished to different caps, so essentially you'll have different scales for each at different % values. You also get dodge from Agility which will be another factor changing the location on the curve and as such the value of the parry rating (defense will feed both equally so we can leave that out of the calculations).
So, you won't be able to offer a X Parry value = Y dodge value for ratings, it'll have to be a formula accounting for dodge rating and agility, versus parry rating, and then you should be able to create a comparison. I haven't sat down to figure out the math yet, but it's on my list to do if no one beats me to it.
Like Sparan said, there's no DR on Stam, or for that matter Block rating.
I'd love to get a formula posted here though, DK's, Warriors, and Pallies will all have the same cap on dodge and parry (though they have different base values so the formulae will each be slightly different, but not wildly).
You can offer a X Parry value = Y Dodge value for ratings. More specifically, 1% Parry (un-diminished) is better than 1% Dodge (un-diminished) if your Parry chance in relation to the Parry cap is lower than you Dodge chance in relation to the Dodge cap (and vice versa). For 'real' decisions (i.e. what piece of gear/which gem is better) you can neglect your Defense rating and Agility -- you just need the values from the character sheet, which do not account for diminishing returns, if i am not mistaken. You need to subtract your 'naked' Dodge and Parry chance from class and talents, though.
Concerning the comparison of Parry/Dodge with other stats, the situation (in my opinion) has not changed. The answer is still: depends on what you are doing or what the boss is doing to you.
The whole dodge and parry being set to separate DRs thing is so ridiculous, btw. Bringing tanks in line in terms of survivability via leveling off armor and putting avoidance on DR (it's not really DR, btw... it's a set return in terms of relative avoidance... it's really just that it's not on appreciating returns any more) is a good thing. But, giving 3 tanking classes two stats that diminish independently and yet produce the same avoidance effect and 1 class only 1 stat (regardless of how much better initial scaling agi has for druids) is going to create MAJOR scalability issues in favor of the classes with 2 stats in the long haul. It's bad enough that 2 tanking classes already have a non-dr mitigation mechanic (block) that scales from 2 different stats that are sure to be itemized on all relevant tanking loot. I just think as we progress through LK warriors and pallies are going to get more bang for their buck out of tanking stats than DKs, who are going to get more bang for their buck than druids.