Addressing the current state of Hammerzon:
What HOZ had going for it previously: High sustain/survivability up until ~135. Wasn't lab viable to begin with but the Hammerz was a decent meatshield with subpar dmg. Over a few patches, they lost 25% max block but gained melee mastery (net benefit as the hammerzon's primary weakness was spell dmg attacks). This was a necessary change but it didn't bring HOZ into the meta. Relegated to farming spec.
What HOZ suffered from previously: Single target damage. Magnetism was a stationary buildup attack that multihit a ton so most bosses teleported away before you could get more than 1-2 stacks, rendering it almost useless for its sole intended purpose. It helped with Riftwalker 3 and a few other niche scenarios but, overall, did not provide a reliable single target. Accordingly, Thundercrack did shit single target as well so Hammerzon was basically funneled into farming exclusively and working around clunky hammer mechanics in narrow corridors. Additionally, the talent tree was split into caster/phys dmg that both scaled from dex (which is hilarious considering you wouldn't even have mana to cast Lightning zon spells - Very strange design philosophy)
The premise of the rework, as stated, was to make Hammerzon less of a "jack of all trades, master of none" by separating the two trees and providing better "PaSsIvE" support for each.
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How did Devs address these deficiencies in their rework?
Talent tree:
Separated phys dmg build (lightning conversion lol) and lightning caster into two distinct branches and making periodic discharge a buff mechanic that would *allegedly* benefit both builds.
Problem: By adding 50% lightning conversion to HOZ, you cut sustain in half and forced an already heavily gear dependent build to forego a lot of +phys dmg gear choices to pursue a suboptimal hybrid phys/-ELR build. (so much for removing jack of all trades/master of none). Additionally, the discharge proc doesn't actually scale the -Enemy lightning resist, it only makes it last longer and increases proc interval (Incredibly useless point investment with very little benefit).
To make matters worse, they removed Melee mastery option from HOZ (which I suppose was intended to reinvent the identity of the build to be more of a phys dmg caster than tanky phys dmg melee). Yes, they added 25% max block but that doesn't effectively mitigated Hammerzon's primary survivability weakness (enemy spell dmg attacks) so the loss was substantial.
Single target:
1) They removed magnetism/thundercrack and replaced it with power shift/reckoning of Zerae.
The intent, I assume, was to provide a more reliable single target ability (power shift) that could be used more dynamically in conjunction with Reckoning so, if a boss teleported out of your tri-hammer rotation, you could at least hit it by fanning the cursor around periodically.
Problem: While power shift's dmg is better single target, you are forced into close range (contradicting the aforementioned build identity) and the 50% lightning conversion literally cut the build's lifesteal sustain in half. You're now far less tanky and forced into precarious positioning in order to do effective damage.
Additionally, reckoning of Zerae does not proc nearly as much as the description would imply and does mediocre damage at best.
To make matters worse, HOZ and powershift now scale off attack speed instead of cast speed so you also cast fewer hammers at max frames.
TLDR; The long-awaited HOZ-rework did more to damage the spec than help it and the talent tree split is nothing more than a gimmick that doesn't effectively mitigate any of the weaknesses HOZ experienced in the past. Survivability is far worse and hammers are now even more reliant on ELR gear than before.
Proposed solution:
1) return melee mastery so the build has some semblance of survivability.
2) Remove lightning conversion for HOZ and provide a suitable passive alternative to discharge (or perhaps make the hammer variant of discharge give - enemy phys resist?)
3) Possibly add a single target skill that you can click lock so you're not running around like a chicken with its head cut off for bosses like Baal who TP every .5 seconds.