I doubt they have the numbers exactly where they want them already though. I would expect changes (and give feedback to help that along) before release. Numbers on almost everything are usually really bad at this stage of a PTR.
Yeah, When they fix double dipping It should be alright, Not to mention at the moment I think this is currently a PvE nerf over last patch so we can probably some damage buffs somewhere. Probably higher Mastery scaling or Frostbolt damage.