Itemization Budgets and Upgrades in WoW.
I wanted to get a little bit away from rogue talk and give some detailed explanation on how itemization works in WoW and how you can use this knowledge to determine which pieces to upgrade first. This is going to be technical so if you are not comfortable with differential equations, you may want to skip over the mathy parts.
Before Mists of Pandaria shipped I was interested in working out how stats were itemized. I had an inkling that the trend was exponential. So I used my trusty spreadsheet to back-calculate itemization formulas. The first thing I did was determine secondary stat allocation by observing that any piece (without sockets) that had equal secondary stat allocation was within rounding of 2/3 of the amount of the primary stat. Using this information I inferred that sockets are itemized at 80 primary and 80 secondary stats, with a meta socket counting as two sockets. This is why helms have a socket bonus of +180 stats (equivalent to 3-sockets bonus). Next I plotted stamina, agility, and total secondary stat allocation against several item levels ranging from 463 blues all the way up to 509 purples (I’ve since expanded this spreadsheet to item level 580) in my spreadsheet. Using this information I added an X-Y scatter plot and added exponential trendlines to get the itemization formula. The functional form of an exponential trend line looks something like Ceki where k is a constant (it’s the same for all stats and slots) and C is a constant depending on the slot and stat type (stamina vs primary vs secondary), and i represents item level.
So when planning out our upgrade path, we want to get the most bang for buck. Without getting into specifics regarding the different scaling values of your individual stats (this should be pretty easy to infer after the information presented in this post). This generally means we want to upgrade the items that give us the biggest increase in stats. Oh my, we’re looking at rates of change. This is exactly the information that derivatives provide for us. Let’s take that exponential function above and use that to come to a surprising (for some, not for others I’m sure) conclusion. Let’s start with our exponential above but make a simple change. First we’ll define the stat amount as S, the item level as i, and the relevent constants as C and k, defining our equation as S = Ceki. When we derive both sides of this equation we get dS = kCekidi. Now if you look at the right side of the equation, we have our original value for S. If we substitute that back and divide both sides by the differential i, we get dS/di = kS.
The question you may be asking is what does this last equation tell us? Well it tells us this: the rate of change of stats versus item level is directly proportional to the amount of stats on the piece of gear. The conclusion to this is that you want to upgrade your better items first, and then follow suit. Without considering the relative value of secondary stats, how do we asses this quickly? It’s very simple: look at the stamina on the piece. The ratio of stamina to primary stats to secondary stats is generally fixed, but sockets can mess up the apparent ratio. The stamina is pretty strictly adhered to and as such is the strongest overall indicator of the amount of stats on gear, with one notable exception.
The legendary cloak is approximately 27% overbudget on secondary stats, so it contributes more than an ordinary item level 600 (or 608) cloak will.
Using the formulas I derived from itemization and item levels for items obtained from datamined Warlords of Draenor items, we can have fun with these and see what level 100 items would look like pre-squish. The datamined engineering helms are at item level 675 according to wowhead. Pre-squish, without sockets, an item level 675 helm would have 9727 stamina, 6485 agility, and 4323 each of two secondary stats. A one-handed physical dps weapon would be 17,565 dps and a two-handed physical dps weapon would be at 23,684 dps. A caster weapon would have 37,134 spell power. At item level 1000, a one-handed weapon would do 362,897 dps, for a damage range of 660,472-1,226,591 for a non-dagger.