7). Your dk is blood-elf not orc, and loses 5 expertise + ghoul damage
8). Jewelcrafting is 1 of the required professions, and the other is not a factor.
9) You did not factor in hit cap as a requirement of your gemming, this is an obvious huge negative impact on dps, an oversight you made during your simulations, and I posted how many free stats are available to you in the original post for gemming and what your end stats would be pre-gems so you'd make sure to hit all the caps you need to. After capping arpen, hit, expertise you would gem strength of course, and 1315 is arpen cap before food and elixirs (1315+85= 1400)
10). Why does your simulation not show blood strike damage, necrosis damage, blood-caked-blades talents, auto-attacks damage?
11). Your gear is not properly enchanted
12). Even in the simulation my build doesn't have proper gems/sockets/enchants (no chant on pants is huge af imo) and no belt gem whereas you have all of it proper.
13). You very much so mis-represented my build with your simulation and you didn't take into account all the factors.
14). My build in your simulation is not expertise capped, hit capped, or actually arpen capped. All 3 are huge factors into my build. Hell even 1 missed scourge strike will severely tank it.