If you're looking to do competitive arena (>2K) I don't think it's worth coming back. If you want a 50% win rate and a shot at the 1600 bracket and 20 minute queues, roll 4x enhancement shaman and find a very patient healer. They're kind of a gimmick in other PVP scenarios though - BGs and world pvp, where 3 minute instagib cooldowns don't win you anything.