There's certainly some correlation between Warlocks going from below average to absolute bottom in representation and the debilitated state Warlocks are in.
Reasons*
Fotm rerollers rerolling, additional rerolling due to hyperbole surrounding the state of the class, literally everything being overhauled on every class so potential to not like new lock mechanics and / or absolutely love a different classes new mechanics, warlocks having literally always been one of if not thee most underrepresented class outside of very specific time frames. etc etc
..and so he left, with terrible power in shaking hands.
But that's true of all classes, why aren't people getting fed up with the changes to their mages and hunters are rerolling to locks?
Coyld it be...playing a warlock is like squeezing blood from a stone?
Something need to be done because right now we're the least played class in WoW
All the MoP rerollers from the snapshotting crisis are finally moving on.
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Anecdotal but I was a Hunter for 11 years and rerolled after what Blizz did to them.
Mages didn't really change. They never really do. By far the most stable class in WoW.