Someone hasn't read many patch notes or dev blogs in a while....
Short version: It's an expansion, shit changes. All CC across the board has been reduced and all tanks have had huge changes to their base mechanics. Saying anyone is nerfed or overpowered right now is pointless, they haven't even started the tuning and balance phase yet. Wait til beta is nearing an end til you decide to switch to a DK tank like you should have before WoD anyway.
Short version: It's an expansion, shit changes. All CC across the board has been reduced and all tanks have had huge changes to their base mechanics. Saying anyone is nerfed or overpowered right now is pointless, they haven't even started the tuning and balance phase yet. Wait til beta is nearing an end til you decide to switch to a DK tank like you should have before WoD anyway.