She says, insightfully, that the reason for this is that Warlocks have just tons of annoying abilities. Fear is probably foremost among them-- with a skilled Warlock, your character spends half the fight out of your control. Soul Link and Felguards are just plain evil (it's like having a Warrior tank for you), and with all those DoTs, a lock is hellfire on wheels (and ten locks in WSG are even worse). Not to mention that since locks love to load up on Stamina, they're tough to kill, too.
It's just MW's timing that I don't agree with-- people have hated Warlocks for a long time now, and I'd say in general that so many classes have been buffed lately that people have moved on. Personally, Hunters are the class that drives me nuts in PvP now-- they still have that very exploitable dead zone, but in a big melee, one Hunter can lay down DoTs and CC and turn the tide of battle. Plus, those NE Hunters in Tier armor just look so smug! A Warlock is still trouble, but my shadow Priest can fear and DoT, too, and no one's bothered by him. It's Hunters that really bug me.