Well supposedly (non-hunter) ranged was kind of bluffed for the most part, but apparently TWW prepatch talents are still in flux. Melee, tank and healing got kind of messy at this prepatch.
Lots of streamers talked about Mages as currently being OP, but that seems also this was pointing @ level 70 so technically if a few of their base spells for up to level 20 are getting the boost then I would think others like the Evokers aren't tuned yet. But frankly not seen much about the Evoker being OP.
Now I would not jump ship because a few current classes are now OP, because knowing Blizzard these "fun detected" will get hammered or such.
These Evokers may be getting bluffed by higher level effects, one would have to check their food, potions and other bluffs on the character.