Your implying that I am saying "It's not fair new classes to be OP, unless its something I play" I didn't play DK's when they were OP myself. Didn't want to, I was perfectly content on my Druid. So that statement is just silly. I still play a Druid my DK is just my offhand class for my guild when they need me to run it. But our guild leaders warrior is always pulling agro off my Blood DK. Its just irritating because then I get complaints from the others that I can't keep the agro when he is pulling it off of me since he is a tank warrior.
DK's blood tank priority is always Mastery comes first. then parry and expertise. Crit is worthless for us period it is never to be a thing we want as we get no added benefits as blood tanks.I've been playing the game from its birth so I understand the concept of tanking myself and how to do it in WoW. Though I will admit I do not have weapons like StarShatter like he does but I do have a weapon that's just as good.
Actually tank priority stats are Hit/Expertise > Tanking Stats secondary. Without hit and expertise now, you won't hold the same threat that you did in Wrath/Cata etc. Without being 7.5% in both you'll drop threat to the tank that IS hit and expertise capped as their vengeance stacks will be hitting (not only harder but) all the time. You are losing threat to tanks that are capped because of this reason.
But I have always been told for a Blood DK (tanking is all you can do in blood) Mastery was the priority, and I was told also a blood DK tank is different than a Frost DK tank.
Bloods the only tank spec yes, but hit and expertise are still needed to be able to compete with dps and other tank scaling. It's a misconception and I appreciate your understanding that I'm not trying to talk down to you but to improve you. Yes, if you aren't hit and expertise capped it will be extremely easy for another tank or a top dps to gain the upper hand on threat and sustain it. Mastery is priority if you aren't having threat issues, you are so I would suggest working on your hit. Anytime you need help my avatar here is the same as my toon. I play on Sisters of Elune, I won't hesitate to give you a hand if you ever need it :).