DK PvP Gear vs DPS GearFollow

What do I need to look for in PvP gear vs DPS gear? What are the best specs to look for? What kind of numbers should I have in Melee and Defense? I thought I had a good set going. I do well in Dungeons, but im getting my *** handed to me in Battlegrounds. Im not sure how to link my toon name is Mandolloren on Blood Furnace Lvl 79. Any help would be great. Thanks. aka MustangPunk