While there are technically specs that are worse than DK, Death Knight is the ONLY class that has no spec above B tier, even enhancement shamans had the option of demolishing people in pvp if they respecd ele. Death Knights were average before 10.0.7, and after the patch they are trash tier. And it’s not looking up for us in 10.1 either, as Blizzard is very careful that the buffs we get are minimal, and on top of them announcing upcoming nerfs today to this #@!% class, they’re giving specs like Arms warriors buffs to ignore pain for some reason. Why even bother giving DKs the death strike buff, when they’re going to buff the classes that counter us even more anyways? Historically, DKs have been decent for about a week, and then been forced down in the gutter for the rest of the expansion, see Shadowlands. So if you want to PvP as a DK, keep in mind that it’s currently one of the worst options, and it’s not getting any better.
I was very hopeful for DK after the announced 25% stamina buff today. Logged on the PTR and tested DS with full Season 2 PVP gear - it heals for 82K baseline. I think it’s not enough, it got buffed by 5-6K at most… Health pools are around 600K.
There is still hope for unholy, because the 150% crit change will affect them very little, unlike many other classes, and with bigger health pools DK might survive a bit better.
But yeah, I think DKs are in a very tough spot. They had the “immortal against casters” niche which kind of balanced it out, but no more.
Edit: oh, one more thing. The new tier set requires that you take Raise Abomination, otherwise you might just play without a tier set at all. So it locks up army of the dead - one normal talent, and raise abom - one PVP talent. And with the 10.0.7 tree you don’t exactly have many talent points to spare…