Been playing all three specs in pvp (and spending too much gold with it >_<) and my opinion about arcane, my favorite spec, is:
Arcane pvp, while having very powerful strengths, is in a disfavorable pvp environment. Were its current skills available in a earlier expansion, it would shine.
The issue is that current pvp metagame has two features predominating that are too severe to arcane's style, interrupts and melee's uptime on ranged classes, since arcane does not have strenghts comparable to other specs out of chained arcane blasts nor a reliable method to chain AB in safety. Since most classes have a form to interrupt casters either often (every 5 or 10s) or with good gain for it (6-7s lockout), depending on stand-still casts have become dangerous for any caster. Ghostcrawlver wrote about it in http://us.battle.net/wow/en/blog/2551279
, worth a read to understand why instants have become so prevalent.
The melee's uptime is also very high, meaning that they can reliably make use of their 10s cd interrupts and force casters to keep moving. It is discussed on http://us.battle.net/wow/en/forum/topic/4079619649
, where plate wearers complain how this increased melee uptime has led to little benefit from using plate armor. The point of note is that kiting through snares have become insufficient to survive, since melee classes have both snares in abundance as well and strong gap closers. Without an extra escape mechanism comparable to Deep Freeze, Dragon's Breath, pet Freeze and snare-removing Blazing Speed, arcane often needs to burn long cds to create a gap when a melee spec gets close, which isn't sustainable in arena for a spec without an equivalent to Cold Snap/Preparation.
The fact that arcane doesn't have a strong safe method to burst is the final point that makes this spec have a high floor skill cap, as you need more setup effot than a frost mage to get the same burst, supposing you aren't being ignored. Arcane blast chain isn't near as safe as a deep freeze followed by frostbolt and ice lance/Brain freeze, or a critted pyroblast followed by combustion + impact and Dragon's Breath. So, not only you need to cut a healer's support, you need to prevent any form of interrupt, including those from the kill target. Unfortunately, this point is too important in arena and is the reason some mages are using shatter + mastery stacking as arcane. It makes Arcane Barrage as powerful as a ice lance with fingers of frost and, with cooldowns (Arcane Power, Improved Mana Gem, spellpower trinket), as damaging as pyroblast plus its dot, but on a 2 min cd.