Nah. UVLS demo warlock was ridiculous OP for like 6 months before blizzard bothered to nerf that for warlocks. While some other OP abilities/trinkets gets nerfed in days/weeks... surely coincidence right?
This just also happened to be expansion where warlocks got all kind special love with their class specific quests too, bit too much coincidence when they are also kept OP levels whole expansion over multiple raid tiers.
For WoD, I am betting for shamans being newest "devsuperfavorite" class.