So let me get this straight.
Tanks aren't allowed to do damage in pvp, therefor they're garbage. Well unless you're one of those guys who thinks zooming around the fight and interrupting randoms, and using some short cc, is actually contributing in any meaningful way.
Ranged dps are garbage in pvp because they can't kite anything, can't cast while moving, nor are they able to survive, so in most situations they just get piled on by melee.
Only exception being BM hunter, but these do so little burst damage, that eventually they run out of cc and gap makers, and their melee target is nowhere near dead.
So basically, unless you're a melee dps, you should just stay away from pvp altogether.
Oh, and also you need to do some serious PVE in order to be good geared for PVP, because PVP gear is worse than what some decently high m+ gives.
"But...but...but ARENA!"
Ninja, fuck your arena, it's even more niche content than PVP as a whole in this game.
Where are the PVP devs? Do they even play their own game?