I don't care if my spec is underpowered or not. I have never played discipline in PvP with my priest, or frost with my mage. I play the spec that I like, maybe holy and fire were less "solid", but both have their own tricks that makes me feel useful, and at the end, I feel more rewarded than playing the "god class".
So for me the problem are not numbers, the problem is that fire is far more boring than before without Blast Wave, Flame Orb, and instant Flamestrike. Unfortunatly there too much priests in my guild to play again Holy >< So Destruction is now the other option, I compared spell by spell and warlock toolbox wins for a lot, only Blink is missing. More tools, more combinations, more fun. In addition destruction has an interesting resource mechanic.
Still thinking about Arcane, the new charges mechanic is OK, with Ice Flows and Frost Bomb could be cool in BGs, but even with this new toys, Pandaria Arcane seems more boring than Cataclysm Fire PvP.