Wut?
Let's just ignore the fact that triple BM Hunter existed in early MoP, and Arms was able to 1 shot.
Let's just ignore the fact that season 5 DKs were a thing, as well as Ret for most of Wrath.
Let's just ignore the fact that some casters were able to nearly 1 shot people back in Wrath.
Let's just ignore the fact that Vanilla PvP was a thing.
Let's just ignore the fact that some eSports games in Wrath ended in 4 seconds due to the immense burst damage the game had back then.
Let's just ignore the fact that before WoD most specs were completely unviable.
Yeah PvP isn't in the best spot right now but it's much more balanced than it was in the past.
EDIT: Also, the first season of an expansion is always shit. I'm saving my judgment for PvP in the later patches.