Alright, so at a very basic level, in order to determine which items are indeed BiS, you have to have a method for determining how much each stat "weighs". Stat weight is basically a numerical representation of how much one thing is worth compared to another thing, so you can assign values to every item to determine how good things actually are, in terms of contributing to damage.
One of the major misconceptions about stat weights, is they were static. People bandied around data like "1 WD is worth 6 INT" or "1 INT is worth 6 CRT", etc. In reality, stat weights vary, sometimes greatly, from one person to the next, from one gear set to the next. In order to actually come up with realistic stat weights, you need a working and reliable damage formula.
This is where EasymodeX, those who inspired him and those who contributed data sets to refining the current formula come in. In this thread, you can see the formula being refined as more data sets are introduced, to get it to the point where a formula can be used for any class, any stats, to come up with a reliable damage number.
So, it's all just hokum, right? Nobody really knows, blah blah blah, right? Well, that was my basic stance a month ago. I believed one train of thought on stat weights. I believe differently now, or more accurately, know better. So, we've got this damage formula: (WD*.2714745 + INT*.1006032 + (DTR-202)*.0241327 + WD*INT*.0036167 + WD*(DTR-202)*.0010800 - 1) * (Potency/100)
The first thing we need to determine an actual BiS, is confirmation that this formula can indeed reliably and more important, accurately, determine damage values from stats. I'm going to give a single example, but in the process of my research, I had many many examples. I sat down in front of FFXIV:ARR, and I literally cast a single spell on a Striking Dummy hundreds of times in some cases. I tested Bio, Bio II, Miasma, Miasma II, Ruin, Ruin II, Fester, Blizzard II and Tri-Disaster. I just sat there, cast spells, wrote down the damage values that popped up. I wanted to eliminate potentially inaccurate parsing results from the equation, as well as record individual DoT ticks for validation.
So, here is an example set of data for Bio that I recorded earlier this morning for purposes of explaining this:
Code:
109 148 105 153 99 108 99 163 109 109 108 101 102 99 110 110 153 106
109 99 99 101 101 109 100 107 165 105 108 105 105 105 100 159 165 100
153 105 109 163 148 108 110 107 106 109 109 102 107 108 165 101 108 110
165 157 103 162 99 106 107 101 154 108 157 105 157 107 109 103 103 101
99 105 101 103 160 150 103 107 110 163 108 102 109 103 110 108 99 99
163 150 160 107 101
This was taken with 71 WD, 490 INT, 280 DTR and 563 CRT. So, before I can compare these results to the formula, I first need to come up with the non-crit values of all of these numbers. If a number was great than 120, I divided it by 1.5 to get the non-crit value. I'm left with this:
Code:
109 99 105 102 99 108 99 109 109 109 108 101 102 99 110 110 102 106
109 99 99 101 101 109 100 107 110 105 108 105 105 105 100 106 110 100
102 105 109 109 99 108 110 107 106 109 109 102 107 108 110 101 108 110
110 105 103 108 99 106 107 101 103 108 105 105 105 107 109 103 103 101
99 105 101 103 107 100 103 107 110 109 108 102 109 103 110 108 99 99
109 100 107 107 101
The average of all of these numbers is 105.031578947368. So, now we take the damage formula, plug my stats and potency for Bio (40) in and end up with this: (71*.2714745 + 490*.1006032 + (280-202)*.0241327 + 71*490*.0036167 + 71*(280-202)*.0010800 - 1) * (40/100)
What we get back is an un-modified value of 80.50345644. Now we need to apply the SMN trait "Main and Mend II" acquired at level 40, that "Increases base action damage and HP restoration by 30%." 80.50345644 * 1.3 = 104.6544934, which is within the acceptable range of +- 5% deviation compared to our in-game data collected and averaged to be 105.031578947368.
So, from this we can conclude that the formula, which again, I tested on far more than just Bio with i89 gear, I tested with 10 different skills across 5 different sets of varying ilvl gear, is giving us accurate results. Since we know we can rely on this formula for accurate results, we can now take to the task of finding stat weights.
For the next exercise, I'm going to use the "old"/current BiS set:
Allagan Grimoire of Casting
Summoner's Horn
Summoner's Doublet
Summoner's Ringbands
Allagan Rope Belt of Casting
Allagan Breeches of Casting
Allagan Boots of Casting
Hero's Necklace of Casting
Tremor Earring of Casting
Hero's Bracelet of Casting
Hero's Ring of Casting
Vortex Ring of Casting
This set confers the following attribute bonuses: 71 WD, 224 INT, 60 DTR, 224 CRT and 37 SS. Add that onto our base stats (with Soul of the Summoner) and we get total stats of: 71 WD, 499 INT, 262 DTR, 565 CRT and 378 SS. These stats are going to be our baseline for determining stat weights.
We start with some basic assumptions.. the aforementioned stats, the aforementioned damage formula, potency of 40 for Bio, our base damage and our modified damage values. From this point on, the base (un-modified) damage is fairly irrelevant, as the modified damage is what is representative of what we see in the game. From here, we need to come up with damage modified by critical hits.
The formula I am using, which again, I have verified with large data sets in game to be accurate with my selection of gear sets is: 0.0697 * CRT – 18.437. This formula came from Valk's work and has been independently verified by multiple people.
So I put my value of crit in and get the following formula and result: 0.0697 * 565 - 18.437 = 20.9435% chance to critical. Now we need to turn this number into something we can multiply our base damage value by, to get a crit modified damage average. So we have a 20.9435% chance to crit for +50% damage. So we'll do something like this: 1 + 0.5*(0.0697 * 565 - 18.437)/100 = 1.1047175. Basically, averaged out, we are applying a 10.47175% bonus to damage for our critical hits.
We take our calculated base [modified] damage of 105.3834666 (calculated using the above formula with the BiS set stats), multiply it by 1.1047175 and get back a result of 116.4189598 damage, modified to include the average crit damage contribution.
Just to make sure nobody is lost so far... for our BiS set stats (71 WD, 499 INT, 262 DTR, 565 CRT and 378 SS) we have a crit modified damage value of 116.4189598. This is our baseline damage that our stat weights will be calculated against. To get our stat weights, what we're going to do is perform this same calculation, but each time with a single stat increased by 1. What this is going to do is give us a damage value that we can compare against our baseline damage, to determine how much damage was added by increasing a single stat by 1.
We'll start with WD: (72*.2714745 + 499*.1006032 + (262-202)*.0241327 + 72*499*.0036167 + 72*(262-202)*.0010800 - 1) * (40/100) * 1.3 * (1 + 0.5*(0.0697 * 565 - 18.437)/100) = 117.6488683. So, the difference (delta) between this calculated value with +1 WD over our baseline is 0.946083514. This number is important, as we are going to divide this number by the delta for INT, to come up with the stat weight for WD. But, before we go there, let's calculate the other stat's deltas.
INT: (71*.2714745 + 500*.1006032 + (262-202)*.0241327 + 71*500*.0036167 + 71*(262-202)*.0010800 - 1) * (40/100) * 1.3 * (1 + 0.5*(0.0697 * 565 - 18.437)/100) = 116.6242629, delta of 0.157925509.
DTR: (71*.2714745 + 499*.1006032 + (263-202)*.0241327 + 71*499*.0036167 + 71*(263-202)*.0010800 - 1) * (40/100) * 1.3 * (1 + 0.5*(0.0697 * 565 - 18.437)/100) = 116.4768719, delta of 0.044547822.
CRT: (71*.2714745 + 499*.1006032 + (262-202)*.0241327 + 71*499*.0036167 + 71*(262-202)*.0010800 - 1) * (40/100) * 1.3 * (1 + 0.5*(0.0697 * 566 - 18.437)/100) = 116.4556858, delta of 0.028250875.
Now that we have our deltas, we can figure out the stat weights... since we want everything to be relative to INT, we divide the stat delta in question to the stat delta for INT, which comes up with a number relative to 1 INT.
WD: 0.946083514 / 0.157925509 = 5.990694731
INT: 0.157925509 / 0.157925509 = 1
DTR: 0.044547822 / 0.157925509 = 0.282081229
CRT: 0.028250875 / 0.157925509 = 0.178887348
For SS, I will fully admit that I have not redone these calculations, because they rely on establishing a specific rotation, applying SS modifiers to each spell, and figuring out and comparing to base (2.5sec) potency totals for a rotation performed within a static time frame. Rather than perform this work for this exercise, since most people will be able to agree that SS has a fairly minor impact on SMN damage overall, I'll simply use the SS weight derived by Eein at chocobro.com of 0.084943755, which about half that of CRT.
We now have stat weights for this particular BiS set of gear. Now coming up with a total stat weight for the set is a simple matter of multiplication... we take our set stat contributions (71 WD, 224 INT, 60 DTR, 224 CRT and 37 SS) and multiply each value by the stat weight, sum it all up and we get: (71*5.990694731)+(224*1)+(60*0.282081229)+(224*0.178887348)+(37*0.084943755) = 709.4778845 weighted INT.
What we see here is that each gear set has its own stat weights, and thus its own calculations to determine how 'good' it is. Previously, we were applying the same weights to every single set to come up with that determination (har!), but that was wrong. So, now that we've got a method, I did some expertimentation with gear sets to find other ~448 accuracy sets that could potentially offer a higher value of weighted INT. What I came up with was 2 sets, identical except for 2 specific slots, that had identical stat contributions and thus identical stat weights. These two sets are:
Allagan Grimoire of Casting
Allagan Circlet of Casting
Summoner's Doublet
Allagan Gloves of Casting
Allagan Rope Belt of Casting
Summoner's Trousers
Allagan Boots of Casting
Hero's Necklace of Casting
Tremor Earring of Casting
Hero's Bracelet of Casting
Allagan Ring of Casting
Vortex Ring of Casting
...and...
Allagan Grimoire of Casting
Allagan Circlet of Casting
Summoner's Doublet
Allagan Gloves of Casting
Hero's Belt of Casting
Summoner's Trousers
Allagan Boots of Casting
Hero's Necklace of Casting
Tremor Earring of Casting
Hero's Bracelet of Casting
Hero's Ring of Casting
Vortex Ring of Casting
You'll notice, the only difference is the belt and non-Vortex ring. You can use either Allagan belt and Allagan ring, or Hero's belt and Hero's ring, and you get the exact same bonuses. Both sets sport 448 ACC, just like the previous BiS set. The calculated stat weights for these two sets are as follows:
WD = 6.120637211, INT = 1, DTR = 0.282081229, CRT = 0.186899974, SS = 0.084943755
If you take the set stat bonuses of 71 WD, 224 INT, 103 DTR, 153 CRT and 48 SS, we get a weighted INT value of 720.2926048, which is 10.8147203 higher than our previous set.
And that's why the new sets are BiS.