Okay, to frame this, I'm just going to explain my point of view and try and understand (form the comments) why Tanks are okay in PvP.
I'm in a RANDOM Battleground (serious, I know) and I came across a Blood DK in similar PvP gear. I'm a Ret paladin.
Inquisition is up, he's sitting in my Light's Hammer, and I pop cooldowns. 5 Holy Power TVs do NOTHING. This guy is invincible. I don't get his HP down below 80% despite a constant damage-focused rotation aimed straight at his face. Now, as a Ret (regardless of talent choices) I know what I'm doing. Well enough.
But to me, this is ruining PvP - maybe I should phrase it like this: this is ruining PvP for me. I'm not a pro arena guy and I've never been much over 1900, but I'm not a baddie.. and I'm not a noob.
Tank damage is obviously 'a thing' in PvE so much so that guilds complained about Prot Warriors not dishing out enough DPS compared to Palas and Druids (or Monks) specifically. But why is it fair that tanks are subject to a baseline 72% damage reduction the same as healers and DPS? They have so much passive health (which isn't nerfed - by that I mean stamina/HP) and tend to use active mitigation to full effect (especially dodges and parries).
This Blood DK was way better at DPSing that I was at Tanking, and he eventually got bored.. COIing me with infinite runes until I got ganked by an infinity-stun rogue.
So why doesn't everyone run around as a Blood DK? They seem to put out decent enough damage, have the same utility as DPS DKs, and have access to the same ludicrous talents.
It just seems.... shit. The idea that a Tank can go into a BG (and I have the same problem with Palas, Bears, and BrMs) and just not die unless there are 4-5 guys whaling on him. And no, it isn't acceptable 'because he's a tank' he might stand toe-to-toe with a raidboss, but he IS NOT A RAID BOSS HIMSELF. I don't expect this guy to have unlimited Death Strikes and other defensive cooldowns in player vs player scenarios.
It isn't fair. I play a Ret Paladin and an Arms Warrior mainly and while I'm aware of their weakenesses, I accept them where they are acceptable. I rely on other players and try to play to my strengths as they do theirs.
Blood DKs especially are just too independent when it comes to surviving. I appreciate active mitigation as an approach to tank gameplay, but in PvP they simply take too little damage. I do not think that seeing my 120k SLAMS turn into 12k Slams against a Blood DK is acceptable.
Am I alone? Should I give up now, or has Blizzard mentioned anything about tanks in non-rated PvP?