First of all, DMH warrior fan here! Over the years I have experimented with many different builds and I'm really glad to see someone achieve that high of a rank in legend with DMH warrior - you must really have mastered the deck. I haven't tried Hakkar yet because I don't have the card, but I'm curious how you feel about it. My understanding is that Mecha'thun warlock isn't popular at all in wild (maybe in high legend?), and in other matchups it's hard to find a turn to drop Hakkar. Against Reno decks you can just win the fatigue game.
My list usually includes at least one and often two Dirty Rats as well as Brann Bronzebeard. Rat is the star against quest mage, helps a lot against Reno decks, and does fine in Secret Mage and Evolve Shaman matchups. Against skillful Even Shamans who hold on to their resources, you just use Rat before Brawl. If your opponent may have big stuffs in hand and you can't kill it, just don't play Rat. For Deathlord however, it's usually the opponent who controls when to trigger it.
Otherwise the list looks very solid. Garrosh is an underrated hero card, weapon and HP both good. Given the amount of whirlwind effect you have, I might include an Execute just to have a safety option against a single 4 7/7 or the like.