Like you said, you dont pvp trinket
To counter sub is to trink during his shadow dance, and he wont kill you. Moreover, he needs to wait 1 min for another shadow dance to use again
Outside of shadow dance: Hemo hemo, rupter or evis( note that evis wont hit much because of the lose of find weakness) = outside shadow dace, rogue is not a threat at all
I play sub rogue and this is what I encounter against other class
Priest: you never kill priest in opener since he has dispersion
DK: Descreat ground, icebound and Blood presence, plate wearer
war: Def stance, plate wearer
Pala: bubble plate wearer
mage: this **** is fking, i cant fuking stun this class, oh wait garrote :P
dudu: bark skin
Monk: nimble fking brew + a trink
warlock: 500k+ hp and blood horror
hunt: flare say hi
Shaman: just afk believe me, Shaman is meatball unless you are resto : Garrote + cheapshot+.......4sec later half of hp gone :D
To sum it up, sub rogue use shadow dance which is a powerful offensive cd ( during that time, combo point flows, control and damage is unmatched)
Thats why blizzard design def cd for a reason right? plus, as you may know some def cd usable while stun, and of course a trinket
IF you dont use or have those above, good bye. When you can fight back, you are almost dead