This game has never truely been in a state to support competitive pvp; every single season you can point out huge imbalances, bugs, hacks, and shady activities. I think the problem isn't the game, it's the community. People are just getting tired of WoW but don't quit because they've nothing better to do, so they turn to whining.
If the game is in no state to support competitve pvp, why didn't everyone stop playing after being 2 shot by DKs in season 5? Or 2 shot by destro locks in season 6? Or 2 shot by anything in season 8? The list goes on, and now that we're all 20 somethings with huge egos we're blinded by rose tinted glasses and refuse to see anything else than "I can't pvp properly because this game sucks atm", and it's only going to get worse.