Hey all, I'm Swol, the main theorycrafter for Ask Mr. Robot.
As of the time of this post, I am seeing Versatility > Critical Strike suggested for Assassination Rogues on many sources like Icy Veins, Wowhead, Noxxic, etc. AMR is showing Crit > Vers. In this post I'm going to explain to you why Critical Strike is better than Versatility. I will also explain why our stat priority is different than what you see on other sources with respect to Mastery. For now, this is all based on single target.
Part 1: Crit vs Vers, a primer.
Part 2: Why are so many people saying Vers > Crit?
Part 3: Agonizing Poison vs. Exsanguinate.
Part 1: Critical Strike vs Versatility, a Primer.
If we look at these two stats without any class-specific mechanics, we can easily calculate their relative value. 1% Critical Strike will increase damage by the same amount, on average, as 1% Versatility. Easy math to show this:
Assume Rupture ticks for 100,000 before Versatility. Assume we have 20% Crit and 20% Vers. The average damage of the Rupture tick would be:
100,000 * 1.2 (vers) * 1.2 (crit) = 144,000
You can just multiply the base by the Crit % to get average damage because all crits do 2x damage. 20% of hits doing 240k damage and 80% of hits doing 120k damage averages out to 144k.
If you increase Crit by 1%, the average becomes:
100,000 * 1.2 * 1.21 = 145,200
If you increase Vers by 1%, the average becomes:
100,000 * 1.21 * 1.2 = 145,200
It takes 350 Crit Rating to get 1% Crit. It takes 400 Vers Rating to get 1% Vers. So, the starting "weights" for Crit and Vers are:
Crit: 1.0
Vers: 0.875
This will be the base relationship for every DPS spec in the game, except Elemental Shamans who do 2.5x damage on Crits.
Now, there are a number of factors that can change this base relationship between these two stats:
1.) Abilities with 100% crit chance or 0% crit chance. (Assassination has none of these)
2.) Artifact traits that increase crit chance. (Assassination has two of these: Serrated Edge (Rupture) and Balanced Blades (Mutilate))
3.) Class-specific Mechanics. (Assassination has Seal Fate.)
Going back to our Rupture example, lets take into account 3/3 Serrated Edge to illustrate why it affects the relationship:
The formula for the average damage becomes:
100,000 * 1.2[vers] * (1 + 0.2[gear crit] + 0.1[serrated edge]) = 156,000
Add 1% vers:
100,000 * 1.21 * (1 + 0.2 + 0.1) = 157,300
Add 1% crit:
100,000 * 1.2 * (1 + 0.21 + 0.1) = 157,200
As we see, adding 1% crit no longer increases damage by the same amount as adding 1% vers. Its relative value is reduced. The percentage of your total damage done by Rupture and Mutilate will affect the relationship between Crit and Vers. Lets make a bold point for people who are skimming:
Versatility's relative value to Critical Strike increases with the percentage of your total damage done by Mutilate and Rupture.
This also tells us that Exsanguinate builds will value Versatility more than Agonizing Poison builds. (And nobody cares about Alacrity builds but they'd be like the Agonizing Poison builds for weights.)
We also have Seal Fate as Assassination rogues. There is no simple napkin math example to illustrate its relative value, but, I think everyone would agree that more combo points is better. What happens, though, is that as you stack more and more crit and get up to crit rates of 30% or more (easily above 40% in BiS pre-raid gear) you cannot help but waste some of the combo point gains from Seal Fate because Mutilate has such a high chance to give you 3 and a decent chance to give you 4. As your critical strike increases, the relative value of Crit goes down compared to Versatility. We have to use a simulator to test this effect. A good test is to get some stat weights with Seal Fate disabled completely. The value of Crit relative to Versatility could never be lower than that, even if you wasted every single combo point gained from Seal Fate. Here is that value for Exsanguinate, which is the "worst case" for Crit's value compared to Vers:
Vers: 6.10
Crit: 6.02
So, using this data, we can see that even if you waste every combo point you get from Seal Fate, Versatility and Crit are nearly equal. Crit will absolutely be a better stat than Versatility if you are using any of the Combo Points from Seal Fate. At high levels of Crit, the two stats become nearly interchangeable. BUT. You have to get a lot of Crit for their relative values to equal out. Icy Veins, Wowhead, and Noxxic all forgot to tell you that! This leads into part 2.
Part 2: Why are so many people saying Vers > Crit?
Short Answer: Because the technique a lot of people use to calculate stat weights is not intended for predicting damage over a wide range of gear.
Without getting crazy into the math (hit us up on our discord or forums anytime if you want lots of details), here is how one should go about creating stat weights for the purpose of giving the community general advice on which stats are best:
Use one of these fancy simulators like AMR, SimC, Shadowcraft and get a TON of data points for your desired talents/artifact. Get data points with gear that is all over the spectrum. High crit, low crit, high vers, low vers, everything in between, etc. We're talking thousands of points, minimum. Find a best-fitting line that matches each stat's contribution using some fancy but easy to google math like multiple linear regression. There is your weight. That weight will tell you how that stat scales in relation to other stats OVER A WIDE RANGE OF STATS. That last part is what so many people forget, and why so much confusion ensues. You need your weights to be a good predictor of damage increase as the stats increase.
Here is how someone would end up with the conclusion that Vers > Crit:
They manually tinker with simulations and gear sets until they have found a set that they deem to be BiS (or close to it) because it simulates to the highest damage they can find. They then do a simulation in SimC and set it to calculate scale factors using the built-in SimC defaults. The defaults will create two data points for each stat that are both very close to the current gear's stats. Those scale factors are then reported to you as the stat weights you should use. That does not tell you what you want to know! Those weights tell you what to do once you've already obtained all the best gear and are hunting for the very last minor upgrade you could get. If you followed those weights and ignored crit for vers, you'd never reach the level of crit you need to make vers and crit equal in value. They are not good weights to use for general advice because they are NOT general advice. They are very specific advice with extremely limited predictive power, meant for people who have already obtained the best gear. The best gear has a lot of crit, because Crit is better than Versatility!
Part 3: Another reason for difference between AMR and other sites.
Besides the whole Crit/Vers weights issue... The weight on Mastery is also different on AMR's default weights. Here is why:
SimC's default APL is heavily optimized for Exsanguinate. All through beta, that talent was massively overpowered and most of the APL development for Assassination was trying to max out this fun, interesting new talent. Near to launch, they nerfed it, since it was crazy OP. They also adjusted Rupture's damage and undid a nerf to Agonizing Poison. SimC's APL is not optimized for Agonizing Poison, so I think a lot of theory out there is undervaluing Agonizing Poison.
Here are some simulations to show this:
Exsanguinate with good pre-raid gear and 19 point artifact path with best relics.
http://www.askmrrobot.com/wow/simula...7b6f05bb9b713e
Agonizing Poison with good pre-raid gear and 19 point artifact path with best relics.
http://www.askmrrobot.com/wow/simula...1f5ff97edbb69b
Agonizing Poison builds will want a higher priority on Mastery than other builds, which explains our current single target weights calculated with the assumption of Agonzing Poison.
Another really interesting find that I've incorporated into my rotations: With Elaborate Planning, it is worth using Envenom at 3+ combo points to keep Elaborate Planning up. You get a little bit of a damage boost by doing that.
Hopefully that all makes sense... if not feel free to hit me up anytime.