Simcraft Supplemental: This thing or that thing?

This post is going to read a lot like the gemming post from the other day. The basics of picking between two upgrades is much like determining the ideal gems or enchants for them.

Step one is, of course, get your scale factors with simcraft. We'll be comparing a couple pairs of items. First up is two itemlevel 245 robes that are available to everybody regardless of the content they're doing, but also a situation where the standard rules of warlock itemization don't give a clear winner. Specifically, the two crafted robes from ToC:

So, we have our scale factors (I'm just pulling the 13/58 cookie cutter profile here):

Intellect=0.41 Spirit=1.14, SP=1.62, Crit=1.05, Haste=1.45

First off, let's talk about the hit cap. I recommend not including hit in your calculations. Rather assure that you're always hit capped, and weigh items only on their DPS stats. If you include hit, you greatly inflate items with hit, but the fact is they're either much higher weighted than that calculation would give (i.e. you're not capped) or they're wasted itemization (i.e. you already are).

Second, note that there's a lot of redundancy in these two robes. We'd be repeating a lot of work to do everything, when the identical portions of the two items are giving the same benefit. It's the differences that make one better than the other, right? So what's the same: Sockets, socket bonus, the enchant you hopefully plan on adding, 103 stamina, 103 intellect, 131 spellpower, and 66 crit.

Wow, that went quick, didn't it? So the decision comes down to 90 spirit (Moonshroud) vs. 90 haste (Merlin's). You can see why the general rules of thumb break down: The choice is very often haste vs. crit when picking gear, which tends to make the decision easy, and why the "haste not crit" rule of thumb is so commonly repeated. However, it's haste vs. spirit here - two strong DPS stats. Since it's equal points, haste's higher scale factor wins.

This is a bit of a trivial scenario, but often just knowing which item has a higher scale factor is enough, provided items are the same itemlevel. Let's toss things up, though.

Let's compare this one to Merlin's Robe (Moonshroud is the clear winner having both more haste and an extra socket for more spellpower). Now here, we'd need to do the work and see if the socket bonuses are worth getting. I'll make things simpler here and pretend they're not.

So paring down the identical stats (stamina, intellect, two sockets) we're left with Merlin's robe having 131 spellpower 90 haste 66 crit and a socket (23 sp), and Flowing Ascent having 140 spellpower 74 haste and 90 spirit. This boils down to a difference of:
Merlin's Robe: 14 spellpower, 16 haste, 66 crit

Flowing Ascent: 90 spirit

Now, the rule of thumb here would tend to lean towards Flowing Ascent, having pretty much the perfect warlock itemization. But, what about that extra socket? Hm... Again, let's look at our scale factors:

Intellect=0.41 Spirit=1.14, SP=1.62, Crit=1.05, Haste=1.45

So this means:
Merlin's Robe:
14*1.62=22.68

16*1.45=23.2

66*1.05=69.3

Total:  115.18

Ascent:
90*1.14=102.6

So the slight edge to Merlin's, but why? Let's ignore spellpower a moment. This leaves Merlin's Robe at 92.5. The spellpower tips the scale.

Merlin's is only better because of the extra socket. Which is an important point - sockets are underitemized when compared with the gems that go in them. Any item with more of them is going to have a higher effective item budget than one with less or none. This is why in BC, where Blizzard was very generous (even indiscriminate) with gem slots, there mid-level blue items that remained best in slot until Hyjal for some classes because they had two or three gem slots, and entry level epics in that slot had none.

This is something to keep in mind: Item budget very often wins out. More of a bad stat can beat less of a good one, but primarily the higher spellpower can often carry the weaker piece. This even holds true of PVP gear. Koralon drops can potentially be better PVE gear than Naxx epics because sheer spellpower makes up for the otherwise terrible DPS itemization. MP5 gear can be a solid upgrade, despite the same problem. There's plenty of reasons not to use either in PVE, including simply not being "that guy" who comes in PVP gear and rolls against healers, but sometimes if there's no alternative, bad is still better than what you've got.