As much as I wanted to like and play Wrecking Ball, I think it’s clear at this point (over 20 hours on PTR and QP) that he’s the throw pick of the tanks.
Here is why you shouldn’t play Hammond,
Grapple is the most unreliable movement ability of all of the dive tanks, while Grapple allows for long distance flanks and fast reinforces from spawn the advantages do not outweigh the disadvantages of the ability. Grapple’s momentum mechanic allows enemies to exploit Wrecking Ball’s character model by body blocking him when he tries to escape, so Hammond has to either commit to a dive or die while trying to retreat from one. Furthermore Grapple has poor vertical movement from static positions, so Wrecking Ball is unreliable at contesting high ground and vulnerable to environmental kills that Winston and D.va would be immune to i.e. Lucio Sound Waves or Roadhog Hooks on Ilios Well.
Quad Canons are significantly underpowered, while Quad Canons have great accuracy and fall off damage their 5 damage per shot, 80 ammo per clip and 2 second reload speed makes them the worst tank on tank weapon after Winston’s Tesla canon and completely unreliable in a sustained fire fight. At 125 dps and a 3 second clip, the accuracy requirement in order to one clip targets is extremely high and you’ll spend most of your time either reloading or trying to finish them off with Grapple and escape with Roll.
Adaptive Shields is the worst defensive cooldown in the game, I don’t have anything good to say about this ability because it’s complete garbage - at 15 seconds it has the longest cooldown of any defensive ability in the game, and if you try to maximize your shields then you position yourself into the middle of the enemy team and feed them 600 health worth of ult charge. On average you’ll get a maximum of 300 shields on a clean engagement into the backline, shields in a duel or 100 shields while escaping. Compare that to Winston’s Bubble, which gives him 600 shields and protection from CC on a 13 second cooldown, and Zarya’s Bubble, which gives her 200+ shields and protection from CC on a 10 second cooldown, and you’ll find yourself to be the least survivable of all the tanks.
While Wrecking Ball has a small head hitbox that he’s able to cover with Roll, he also has the largest character model in the game. Character’s like Roadhog, Reaper, Soldier 76, Sombra and Torbjorn can’t miss a bullet on Hammond, so he’s really specific towards having high survivability vs Widowmaker and McCree and that’s about it.
Proximity Mines is a pretty worthless ultimate, while they can be useful for claiming space on the objective generally what happens is the enemy team will use one of their ultimates in order to clear your mines and kill one of your team mates - they end up ahead on ultimate economy in a 6v5. I think this ultimate may actually be worse than Orisa’s ultimate as far as the tank roster is concerned, because while both ultimates are vunerable to counter ultimates Proximity Mines rarely provide any value in a team fight.
Wrecking Ball is easily hard countered, be it Roadhog, Reaper, Mei, Sombra, Doomfist, McCree, Ana or Brigitte it takes very little to shut down Hammond, what should be a character who goes straight into the enemy team in order to maximize his disruption and shields is a character who has to very carefully avoid any potential counter because even a stun is as good as ringing the dinner bell. And normally that would be fine if he were any other dive tank, but the dexterity of movement on Grapple simply isn’t there compared to Leap and Boosters in order to get clean engagements on isolated enemies and it feels very counter intuitive to play him that way when Adaptive Shields and Piledriver are begging for you to go big.
Roll and Piledriver are really what makes Wrecking Ball what he is, being able to quickly maneuver around the battlefield and disrupt the enemy are great abilities but they simply aren’t enough to justify him over D.va and Defense Matrix or Roadhog and Hook as either the off tank or the third tank on the roster most of the time. And while the prospects of triple tank dive are rather exciting, I feel that if triple tank dive is the only composition you can justify him in then you’ve basically failed to add anything of value to the roster.
I don’t know how you should go about addressing his problems, but you seriously need to look at his kit because it’s not doing whatever it’s you designed it do - he’s basically at release Orisa levels of bad right now.