I suspect 5s went to shit in large part due to the CC-fest we had in Mists. WoW has always been a bit heavy-handed with character progression so all characters tend to be complicated on top of having 10 in a single instance of PvP. It lends to the notion of it being a clusterfuck.

It might not be that bad with all the classes pruned now but no way of knowing until trying it out.