Sub Rogue low dmg

Why is sub rogues dmg so low ? im 530 and i have a pridefull on use trinket and when i pop all cd's and have 5 combo points on a 510 player im lucky if i get a 40k evis out of it and don't say anything like "well rogues takes skill u just suck thats all" cuz ive been playing sub rogue on 5.4.8 for 2 years now im not a 3k rated pro or anything but i deffentely know how my dmg rotaion and burst goes and i know that this is not how rogues are suposse to be in 5.4.8 so would love some answers as to why this is, did rogue suffer a nerf or is the class just bugged ? also would love to hear from someone who is 550 if the dmg gets better if u could tell my what kinds of crits u get when u burst on a 550 rogue or if i should just quit and wait for a buff

You're definitely doing something wrong... I recommend watching Sativ's videos on YouTube covering subtlety rogues in 5.4.
My guess is that you're just not stacking passives correctly which is probably the most common mistake as a sub. Make sure you've got sanguinary vein running by making your target bleed (rupture, garrote or hemorrhage if glyphed into that). Also I personally like using the "Prey on the Weak" talent which fits sub playstyle quite well, seeing as you're going to want to reset quite often to refresh Master of Subtlety.
When bursting, i often enough get ~180k eviscerate crits on my 550 rogue.

Also the recommended stat priority is mastery > crit > haste, and sub usually goes with two daggers.