Out of curiosity, I actually went to Tirkai Woods last night and killed the mugatos for about half an hour last night before the patch. Then I repeated the same farming method after the patch tonight.
On a fundamental level, the changes to Zerkers that Bluehole has made seem to be derived from how people play Slayers. Everything that Slayer does chains into Overhead Strike, except for OS itself which chains into Measured Slice. So when I play my Slayer just soloing the quest mobs, I'll do Knockdown Attack -> OS -> Leaping Strike, then Whirlwind -> OS, then Heart Thrust -> OS, then Stunning Backhand -> OS. However, what makes Slayer so powerful is the fact that you get a glyph which grants 20% chance of cooldown reset on OS. So what actually happens a lot for me is KA -> OS -> LS -> OS -> WW -> OS -> HT -> OS SB -> OS in a single chain without interruption because of how often OS's cooldown resets. If anything is actually alive after this, a quick Fury Strike usually sorts out the last bit of the mob's HP bar. Playing Slayer is like watching a lawnmower cutting down the mobs like grass.
So, what BHS did with Zerker was basically pattern it after how Slayers play. Vampiric Blow has become the de-facto Zerker OS, as the base damage was buffed and it now chains directly out of Cyclone, Lethal Strike, and TS. You can even interrupt your Cyclone before it finishes to chain it into VB. It doesn't require charging at all when chained for full damage, but the healing effect is lower. This makes it effectively the same as Slayer's OS with the 3% healing glyph. However, the flaw here is that there is still no glyph that gives VB a 20% chance to reset it's cooldown. So you can't chain Cyclone -> VB -> TS -> VB -> LS -> VB like a Slayer chains OS. This means a Zerker still can't spam chained skills the way a Slayer can for maximum burst DPS output. The idea is sound but incomplete.
The other thing that BHS did to help make Zerkers attack faster was give Flurry of Blows a 20% charge speed increase. If you have the 25% charge speed increase on Cyclone glyphed already and activate Flurry of Blows, charging Cyclone is very fast now. The only problem is that FoB lasts for 15 seconds and then has a 45 seconds CD, again with no ability to reset the CD. So for 15 seconds a Zerker is actually within striking range of a Slayer's DPS, then for 30 seconds she sucks again, and then for 15 seconds she's decent. The good news is that a previous patch made it so Unchained Anger depleted your HP only minimally, so now you can spam Unchained Anger in between FoB with the glyph which gives 25% chance of activating FoB and that helps keep you in "Fast Charging" mode more consistently. Zerkers were always mana-starved so being able to spam Tenacity, Triumphant Shout, and Unchained Anger helps the mana situation a lot, plus a chance to active FoB while it's on CD is a huge benefit.
A number of other changes were made which are mainly for PvP, such as having Staggering Strike chain into Flatten. Inescapable Doom has it's radius and duration reduced, but it's CD as well. Mocking Shout now actually grants immunity to Stuns and KDs for 7 seconds, which means a zerker actually has a chance to hit another class once or twice before getting stunlocked or serial-KDed and killed. None of this matters much as long as zerkers wear their special super-soft plate Metal armor which grants then roughly 50% the damage absorption of a Slayer's diamond-hardened Leather armor. Zerker is still the worst PvP class by a wide margin but with PvP as broken as it is, this hardly matters. Nobody gives a fuck about Tera's PvP anyways, not when it takes 4 people focus-firing a Priest to kill him and other bullshit like that.
So, what happened to Zerkers 2 months ago in Korea and today in NA was a step in the right direction. But more needs to be done before a Zerker and a Slayer are on a level playing field in terms of PvE DPS. We'll ignore PvP here because it's such an unbalanced mess and fundamentally broken unless Bluehole completely revamps it for every class. First off, if BHS wants Zerkers to chain-spam skills like Slayers, they will need to give CD reset glyphs to Zerkers. If not, then the fundamental issue of Zerkers attacking more slowly than Slayers but their skills not having higher base damage and crit percentage to compensate still needs to be addressed. That's what it boils down to.
Making Zerkers into watered-down Slayer-Lites is not a complete solution. If they are serious about completely Slayer-izing the class, they need to give Zerkers Headlong Rush and actual real stuns which actually do useful things. A Zerker has absolutely no group utility right now compared to a Slayer. I don't even care if Zerker gets a Backstab or not, but for God's sakes, Zerker NEEDS Headlong Rush.
Most importantly, they need to commit to either Dodging or Blocking with Zerkers. Right now Zerkers have a shitty Block which only works about 40% as well as the Lancer and Warrior Block, and a shitty Dodge which only works if you trigger it while charging a skill with a long CD. Since skill charging was sped up in a previous patch, and is even faster now with FoB active, the window of opportunity to trigger Evasive Smash is very small. A half-assed Block and a half-assed Dodge is much worse than the real dodge that Slayers and Warriors get, or the real Block that Lancers and Warriors get. BHS needs to decide, do Zerkers Block, or do they Dodge? And then they will need to either give Zerkers 100% the Block damage absorption of Lancers and Warriors, or give Zerkers a Dodge which can be used freely every 4 seconds like Slayers and Warriors and which has a CD reset glyph as well. I don't care which, but for fuck's sakes, make a decision and stick with it.
So, we'll see if BHS continues to take player feedback and adjusts the Zerker more. It's clear they are trying to do something with the class. It's getting better, but I still agree with most people when they say a Slayer is still hands-down a better melee DPS class than a Zerker.
Oh, right. What's going on with Mystic, BHS? Are you going to take them on soon and start improving them?