I'll try to make this short, just something based on personal experience I got today.
I play as a hunter. I do PvP, mostly BG. Decent gear atm. Since 4.0.1 epic fail in case of my, hmmm..., "power level". Before patch I was fine.
Now here is funny thing. Today I was at friends house. He plays as several classes. One of them a mage. PvP gear a mix of relentless and wrathful. I asked him if I can make a few WSG to try it out how strong mages really are. From two specs he had I picked arcane. Long story short, I completly pwned on all 3 random WSG I got. The thing is, I never ever played a 80 mage before. I didnt used any custom keybinds, just 1-2-3-4. It was not even my keyboard, not my mouse. Different PC etc. I was just pressing buttons and people exploded. Now I'm back at my house, just did a BG with my hunter. And I'm in trauma. I still remember what I did 3h ago with a mage (first time controling a mage ever) and I want to cry when I compare that to my main character with which I'm accustomed since several years.
This. Is. Just. Sad.