its been quite some time since i pvp'ed on my lock. back in bc i used to do arenas with a disc priest in 2s and bounced around in the 2-2.2k range thru season 1-3 as demo and destro. never really buying into the sl/sl playstyle because quite simply i couldnt stand it. i was pretty successful as well in 3s with the same disc priest and a hunter, again playing the demo and destro specs both at the 2-2.2k range
healers caught on pretty quick back then and started dispelling my immolate which in turn cut down on my ability to conflag which is a major part of a destro's rotation. in wrath it wasnt so much a problem because the games didnt always last long enough for either team to get a full rotation off. and although i didnt pvp much on my lock it seemed like destro started going downhill after s7.
here we are with cata, where dispelling is supposed to mean something. it doesnt, healers often dispel UA without even thinking about it. the silence is manageable and the dmg is laughable, but affliction is the most represented spec. if theyre willing to dispel UA they have no problem dispelling immolate. my suggestion would be to make a talent a couple tiers into the destro tree that will reduce the cast speed of immolate by 100% for 3 secs after its dispelled.
like i said its been awhile since i pvp'd on my lock. it was my first toon i ever created and the first one i leveled to 85 when cata hit but i havent done many arenas in this exspansion, im just giving my opinion based off what has occured in my past experiences as a destro lock