170 DEX, level 90 Almace (D61), and lets go ahead and assume capped dSTR (+14 base damage.) So you're looking at a 161 base damage weapon. You're a Red Mage, so your Critical Attack bonus is low or nonexistent. Assuming you have initially capped Ratio and are fighting a level 100 monster, your cRatio is capped to 1.75. This still lets you hit 3.15 (capped pDIF), so lets use that as the pDIF value. You probably don't have any Triple Attack on RDM, so lets assume the maximum is two double attacks.
3.15 * 161 * 5.45 = 2764 absolute maximum damage with two double attacks and all four hits criting with maximum pDIF and an appropriate elemental gorget/belt.
At a cRatio of 1.75, your
average crit pDIF will be 2.774. With 20% Double Attack in your WS set and an appropriate elemental gorget/belt, your
average fTP would be 3.85. There's no way you're fSTR capped on Voidwatch NMs. Lets keep that assumption though, because Voidwatch NM stats seem to be part of the argument. Lets also keep the 100% Crit rate, for the same reasons and because we're assuming constant Champion's Tonic/Stalwart's/etc. However, lets toss in the 95% hit rate cap here just because we know it exists and we're now interested in the average.
161*2.774*3.85*.95 = 1633 Average damage
So, using math that benefits you incredibly and encompasses all of your assumptions, you're still falling short of the average you claim to have. I'll note that we've essentially assumed Voidwatch NMs are Giant Bumblebees with extra HP at this point and that you certainly aren't capping Ratio or fSTR on actual Voidwatch monsters.
Not only do you not average 2k CDCs on Voidwatch monsters, but you don't average 2k CDCs on anything outside Abyssea.