the EP value is pretty low on ArP for mutilate but you have to consider how much of our overall dmg isnt effected by it at all. The stat helps white dmg and mutilates, thats it. Everything else we use already ignores armor, yeah I have some ArP but wearing a piece of gear with a heavy amount of its ilvl sunk into ArP means theres probably another piece of gear with much more agi / ap / crit / exp out there that would yield more overall dps. If I can avoid it I will not itemize for a stat thats only working part-time.

Your final speculation was correct - the EP value of Armor Penetration is quite low for mutilate - around 1.3-1.5 versus hit/crit/haste/exp which are all around 1.8-2.0.

A piece of gear with an ilvl of 264 only has so many itemization points that can be spread around, and if a large chunk of these are spent on armor penetration, it's a safe bet that that piece of gear can be considered "poorly" itemized for mutilate. This doesn't necessarily mean that it isn't good for mutilate (for instance, a few of the current BiS mutilate pieces have armor penetration on them), just not as good as it could be if it were better itemized. Also, I believe white hit rating is much better for combat than armor penetration is for mutilate.

I'll agree that there is too much whining about itemization going on though for several reasons. The 4 piece set bonus is somewhat lackluster, we have already seen several offset pieces without armor penetration, and we have only seen a fraction of the entire loot table.

Starting with 3.2 when they buffed envenom, assassination spec based on eviscerate and arpen stacking with double IP poison has stopped being a competitive spec. The moment you start using envenom, armor penetration loses a lot of value.

With weapon swapping the EP value of armor pen was less than 1.4. We do not know the EP values for 3.3, but I think all stats, including hit for combat past the spell hit cap will be much higher than 1.4. The new DP mechanics will boost the value of hit for both specs. So it is somewhat of a concern that arpen has so little value for mutilate. At the same time, other stats, such as agility and attack power, have more value for mutilate compared to combat, so you should not complain about a single stat. Instead let's wait for the big picture and compare the specs in full gear sets.

At the risk of pointing out the obvious, I think a few points need to be made and perhaps taking a step back and looking at things from a broader perspective would help:
- While probably unintended by Blizzard, an unpopular stat like ArP on Mutilate gear might help a little in bringing the spec closer to Combat, since the poison change made Mutilate so powerful at single-target DPs.
- It's the last patch in LK's content cycle. I'm not sure we're going to see tremendous efforts on Blizzard's part to accomodate every spec.
- It won't matter in Cata, where gear will have Mastery, which will boost stats directly related to our spec.

Ultimately, rogues are fairly dependent on their weapon drops when it comes to picking a spec. It might be perhaps more interesting to focus on weapons and theorycraft whether upgrading by one tier is worth switching spec. Such as getting a main hand dagger one tier above your sword/axe/fist weapon. I doubt we've seen every weapon available in Icecrown Citadel, but that's an angle I wouldn't mind seeing explored.

I finally have a working beta version of the simsheet with the recent 3.3 PTR changes. I will focus on mutilate since that's all I had time to play with for now. The following findings are based on the beta version of the simsheet, so take them with a grain of salt. I will add however that the findings are consistent with the results we saw with weapon swapping as the recent PTR changes in part mimick the weapon swapping effect on dps.
-2-piece bonus is worth about 290 dps in 3.2BiS
-4-piece bonus is worth about 120 dps in 3.2BiS
-Adding rupture to mutilate rotation lowers dps by over 200 dps (even talented and glyphed), envenom-only rotation seems to be the rotation of choice in 3.3.
-51/18/2 is ahead of 51/13/7 by about 100dps even with 4-piece set bonus.
-Master poisoner is still much stronger than Turn the Tables. In fact now MP is second strongest talent after HfB (approximately 4% dps per talent point).
-4+ cycle is still ahead of the 3+ cycle even with the 4-piece bonus in its current form, however, the gap is not statistically significant.
-Energy pooling to 60 before an envenom does not produce any statistically significant dps changes.
-Mongoose and Berserking have about the same dps value, with Berserking having a small not statistically significant lead.
-In terms of strength of stats, Haste has about the same value as AP and both have more value than white hit and agility. So at least at this point it seems the gemming will involve AP and haste. Items with haste procs and high haste amounts will be very valuable for mutilate. However, these conclusions can change as I add ICC gear, which according to some reports is low on hit rating.

Thanks Mavanas, I'm excited to see these changes coming soon. It makes a lot of sense that since DP isn't a PPM poison, that haste value for Mutilate is going to sky-rocket. I am wondering though, will there be any new weapon speed preferences, or will it still be slow MH, fast OH?

I know that OH preference will stay as fast, I am just wondering if the changes will affect MH speed preference.

I think the general consensus, at least as I recall hearing it, is that the commonly found speed differences in Fist/dagger setups versus a Hack and Slash setup are generally about the right to balance out the inherent differences in the spec's themselves. Namely, in theory, HnS is superior to CqC, but Fist weapons have a reasonable chance to go up to 2.7 on occasion, and daggers have a chance to go down to 1.4 on occasion. Specifically, we've gotten that .1 speed bonus in each tier, Naxx had a 1.4 dagger, uld had a couple 2.7 fists, and ToC has a 1.4 dagger. So with the speed difference, it brings the two specs a lot closer to "even" overall. So to answer your question, I would guess that if anything this would potentially tilt CqC a little further away from "even" with HnS with some combat gem hasting *In Theory*. But as we all know, theory isn't always enough. If Ald's calc on some final IIC stat totals end up where he thinks they will, CqC may be entirely obsolete once we start filling out in ilvl 264 gear. To put ourselves in the actual situation of practice, consider where we'll end up with arp in ICC. Most likely dropping an arp trinket and pushing for a hardcap setup, which means the weight of arp is just going to climb and climb, and we'll likely have the room to stack as much as we can afford if it turns out to be our best stat. Obviously you can't really answer definitively without plugging it into a sheet and checking the weights in a full ICC gearset, which I'm guessing Ald will be able to check for us at some point if he has some spare time.

I had time to work on combat in the 3.3 simsheet. Since a lot of gear ilvl 277 gear is still not uncovered, I focused on ilvl264 pieces instead. I also did not model Black Bruise, Whispering Fanged Skull, and Deathbringer's Will due to lack of data, but I will talk a bit about Deathbringer's Will at the end. I have tried three basic setups: 1) Poison oriented spec, 2) SARP - soft armor pen cap, 3) HARP - hard armor pen cap.

1) Starting with the first one, which in terms of optimal gear and gemming is similar to mutilate. 18/51/2 is the optimal spec, and putting the 2 points into Improved Poisons instead of Relentless Strikes does not result in a dps increase. The spec favors gemming AP and haste as well as gaining expertise and poison hit caps.
2) SARP is based on picking up "good" armor penetration pieces and gemming armor penetration up to the soft cap with Needle-Encrusted Scorpion trinket. Obviously the fact that the trinket is ilvl232 takes a toll on it's dps potential; however it appears currently to be slightly ahead of poison-based combat. Gemming after armor penetration soft cap is based on agility.
3) While currently the third spec scores lowest in dps, it has the highest potential as more gear gets discovered. This setup is based on focusing on armor penetration, while holding the 4-piece t10 unchanged (honestly I did not check if it's worth breaking the 4-piece and picking up better armor penetration pieces, it may well be). Gemming is completely based on armor penetration. This spec also has highest potential for two other reasons: a) Deathbringer's Will has passive armor penetration which will help toward the hard cap. I tried putting the passive amount of armor pen on DVH and assuming the same proc and even with that HARP pulled ahead of the two specs b) So far I have not seen any new maces. However if there were maces of ilvl264 with the stats of the axes that have already been discovered, HARP would be 500 dps ahead of other combat specs.

Some general findings: rupture is suboptimal for all three types, instead use eviscerate, glyphed and talented. As a last note, mutilate is far ahead of best numbers I've seen for combat, even though there is no new offhand dagger discovered. The difference in dps between combat and mutilate appears to be of the order of 3k dps currently, so I can feel some further changes coming.

Is it correct to say the mutilate spec would be 51/18/2 and gemming 10 agility/haste or 10 agility/hit depending on the one's current hit rating? Does the recent change to poison and murder really produce such a large gap? Does hard armor pen cap spec (#3) already possess 1400 armor pen? I am honestly not sure what gears you are using in both spec, so I apologize if I seem to be bombarding you with questions.

Yes 51/18/2 comes out ahead despite the fact that 4pt10 favors full relentless. The gemming ends up AP, hit and AP/hit because due to itemization, mutilate is plagued with crit capping issues. Also you want to gain expertise cap because it helps reduce the crit capping problem among other things.
As for HARP, you are still below 1400. You could reach 1400 with Deathbringer's Will and mace spec, if there were ilvl 264 maces.

Berserking uptime depends on your haste. In ilvl264 gear I am getting as much as 43% berserking uptime on the offhand and 63% uptime on the mainhand. So if you are going to replace anything, it would be offhand. On average Berserking on the offhand gives 400*43%=172 EP. A proc with 35 ICD, 15% chance to apply, and 10 second duration has uptime of 27%, so will result on average in 67 haste. Even if haste is 2 EP, Black Magic will give you 134 EP compared to 172 from Berserking.

However, when we discussed Black Magic before, we talked about tracking its ICD and swapping a weapon with that enchant once every 35-40 seconds for the proc. I suppose you can have an extra mainhand and offhand for extra uptime of Black Magic. Of course it goes back to weapon swapping that Blizzard is trying to do away with, but this time around it will be much easier to track it and swap manually. I think Blizzard was more concerned with players needing a certain addon to remain competitive.

Given the strength of haste for mutilate come 3.3, does anyone have opinions of the Emblem of Frost trinket versus alternatives? I have heard people express distaste for the stacking AP mechanic, but that's a TON of passive haste.

It is a powerful trinket for fights that you know you won't drop the stack on. Number of fights where that is the case is yet to be determined in icecrown. But it does seem to be a very competitive trinket for those who are unlucky enough to not have either version of deaths choice/verdict, or for when it comes time to drop mjolnir and go for hardcap setups.

It appears to be stronger than the heroic DV for both specs if you can keep the stacks up. There are ways to keep the stacks even if you have to move away from the target. I mean we kept the stacks up by doing the Heigan dance and shooting him each time we stopped for a split second.

Yea, but keeping the stack up that way risks wasting the ICD on your other proc trinket at which point it may or may not actually be worth doing.

There has been a lot of talk of Mongoose weapon enchant closing in on and surpassing Berserking going into T10. Is it safe to assume that Berserking will again be on top near the upper levels of T10 gear due to crit capping? Or will 2% haste be that valuable?

From what we've seen so far, the itemization on t10 gear is low on hit which pushes our crit cap way down. Until we see a full list of gear, there won't be a definite answer, but with the way things are looking right now, 240 extra Agility will most likely push us over the cap or at least bring us really close. Furthermore, the DP changes also increase the value of AP because of the role it plays in poison damage, so Berserking looks like it'll come out ahead.

Yes for mutilate.

With the purposed DP changes and the "ideal" spec 20/51/0 with 1/3 in Vile and 4/5 Imp; will this warrant a switch from WP to IP on the Main Hand for combat?

If you have talent points in Improved Poisons yes I would presume so.

I think IP on your MH-weapon may even be viable without points in improved poisons.
The reason is that the average damage per weapon hit differs by about 40,5 dmg between IP and WP, regardless of AP and weapon speed (though I am ignoring anything that makes poison dmg scale by a percentage, like crit chance and points in vile poisons). However, the difference in actual dmg between a proc of WP and a proc of IP does scale with AP. At 4k AP, this difference is about 309 (again ignoring crit chance and similar).
All in all, whether or not IP on your MH-weapon is a dps increase with the DP change depends on how many swings you do with each weapon, but my guess from these numbers is that IP will be an upgrade no matter what, regardless of whether you have points in improved poisons.