There’s a fair bit at play here, but let me break it down so maybe everyone stops complaining so much about the state of matches.
#1. Team play in general has declined over the past year. Various power creeps plus folks quitting (I’ve seen some longstanding vets and friends quit for good) has pushed the game away from team play both with it’s players and with the heroes.
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#2. Power creep and failed “balances”.
Tracer and Soldier are the obvious suspects here. These two heroes can find so much value against so many team comps and tank comps in particular. Tracer can easily play past barrier tanks and farm their supports and DPS, leaving tanks stranded from team resources. This means if you’re playing Rein or Monke and all of a sudden Tracer is on your Ana, you either shield bot/AFK or explode. It’s very boring and frustrating. Why be restrained by your own team when Hog and Ball exist? In the same breath, D.Va is the best peeler in the game and one of the few tanks who can actually bully Tracer AND protect her DPS/Supports from Tracer. At the same time, D.Va can eat CC and dmg for her own Tracer, thus hyper enabling her.
While D.Va would be strong regardless of what DPS are good, the fact Tracer is strong only makes D.Va stronger.
Soldier has never really been a tank punisher, but in his current state, he can keep pressure on passive frontlines by sitting back and poking out resources, while also being able to punish out of position squishies from range. In fact, if Soldier maintains a +21m distance from enemy tanks, only Orisa is capable of hard pressuring him. This means S76 can just hard exist at midrange and blow up a helpless frontline until enemy DPS do something about it. While I think Orisa is actually a really strong hero to play into a Smurf/Carrying S76, Hog and Ball can also easily punish the hero while he is quite helpless against both, even with a Mercy pocket.
Hog and Ball have favorable matchups against Soldier, while being able to mostly ignore whatever Tracer is doing. They survive without team resources and don’t need team input to secure picks. The latter is definitely their driving force, but the fact Tracer and S76 are good is going to drive more independent play from tanks.
Let us next discuss the three supports who have helped lead us to Hog+Ball.
Brig is incredibly strong at the upper ranks right now. She has more favorable matchups vs these tanks than most other supports, but her survival is still cooldown dependent when facing them. On the flip side, Brig can really enable her own Ball, while also making Hog virtually unkillable by playing around him. It’s a twofold measure, but basically Brig doesn’t get instantly deleted vs Hog+Ball, and she can hyper enable both.
Bap has little chemistry within this comp and is quite weak against it. This is one of the primary reasons we are seeing Ball and Hog, who can mostly ignore Bap’s cooldowns and damage and just delete him. Immortality Field is still broken, but Hog and Ball are two of the only tanks capable of hard disabling it’s effects. Whether it is Hooking, Whole Hogging, Booping, or Piledriving enemies up out of I.F. these tanks can just ignore the stupidity of the ability. As a Rein main, there’s nothing worse than MTDing the other Rein, only for Bap to Lamp him and then he kills you. Playing Hog and Ball against Bap is quite satisfying knowing that you can still drop an enemy despite I.F.
Last up is Zen, who has mixed purpose within this meta and how we got here. Zen can hyper enable Ball with Orb and Discord, while on the flip side also being able to put heavy pressure into defenseless Hog+Ball comps. Discord is still wildly broken, and as such it is one of the reasons tank players are opting for the hyper survivable Ball and Hog. Getting Discorded as Rein or Orisa in high ranks is basically a death sentence. Hog and Ball have increased popularity thanks to their survivability against Discord.
A decline in team play is still the primary factor for these tanks taking over, but understand that the state of DPS and Supports has only further bolstered these tanks in the meta. Strong solo play DPS will encourage strong solo play tanks and strong solo play supports. As long as solo carry heroes are at their strongest, we’ll remain in this meta. We need team oriented tanks (ie Winston and Rein) to get significant buffs in order to shift this. It’s far easier for 6 players to just hunt for and secure 1v1s than an entire team stack on a Rein or Dive with a Monke.