You were concerned about haste(I guess) and reacted by nerfing cast times heavily.
But now...we have a ton of hard hitting instants around.
And then it seems like you balanced many specs around these hard hitting instants to the point where cast times will be a much smaller part of PvP @ 85.
I've played Mage a fair amount since 4.0+ and it really is just lower quality game play period to spam instants so much as a ranged class. It's also stupid how strong certain specs and specific abilities are against cast time spells now, to the point where you might as well not cast against them at all.
Feral vs Frost duel is one obvious example, and I'm not picking on feral specifically or saying duels matter - this is how it will be like vs. many comps in arena as well.
At no point in a duel with a feral should I bother attempting to cast a spell until his trinket is on CD and I have him deep frozen. Feral mobility and control simply does not allow for spell casting, for a mage anyway. Warriors will be like this vs. many casters as well, and probably subtlety rogues.
I'm not calling melee overpowered, I'm saying both melee and casters have been taken in a bad direction. You can't react to instants in the same way you can casts, and that's a big part of what made casters unique and fun. You have powerful spells but your opponent can react to stop them. Now, we have powerful instants, and there's no real stopping them, with casters vs. melee you are often both just spamming instant damage into eachother.
It just feels to me like PvP has devolved. I know not every spec has a spell comparable to IL but TBH I don't see how you're going to be able to play a caster that still does rely on getting medium-long cast time spells off in this environment.