DH is undoubtedly the biggest problem, but bear in mind that he is only part of the larger issue. Thing is, most control decks have received too few new tools compared to aggro and they simply can't keep up with power creep. DH crushes everyone, but so do Face Hunter and Aggro Rogue. In fact, only Control Warrior can stand up to them... to some extent.
This is not okay. Blizzard is once again allowing some classes to disappear from meta entirely. If nothing changes in the near future, they might as well delete Priest, Warlock, Druid and Mage.