Heart of the Swarm has been out for over a month now, and we've yet to see a single balance patch so far. We've seen a full tournament run to conclusion, weeks of Proleague matches, and an entire GSL Ro32. So far, I'm not convinced that there's a real “balance” problem. But there are problems, to be sure, and Blizzard has finally decided now is the time to start addressing them – announcing that a potential balance test map could be hitting Bnet in the next few weeks.
The balance team's primary objective is to address the feeling that after the first five minutes, ZvZ currently forces you into Muta vs Muta – resulting in a boring Muta blob vs Muta blob fight that is decided entirely by who made more Mutas and had better upgrades. See: RorO vs Crazy from GSL. Blizzard's attempt to answer this problem is to buff the spore crawler's damage versus biological – a change that literally only affects Zerg vs Zerg. The idea is that this would allow players to build up anti-air defenses, such as Infestors or Hydras, and apply pressure while not having to worry so much about defending their base from Mutalisk harass.
This change certainly will help with regards to the early to midgame – putting a few spores around your base will do a lot to deter Muta incursion when their numbers are small. But thanks to their regeneration and speed, the likelihood of losing any is pretty slim at best. And once you build up enough in your flock, they won't care about the spores.
The problem is really just that Mutalisks don't have any exciting interactions with any other Zerg units. They're objectively a counter to a large amount of what Zerg has to offer, and overwhelms the rest in higher numbers. The Infestor – the only real counter in their arsenal – still works, but in its neutered form it's considerably more difficult to use. Thanks to their innate regeneration, assuming they escape chain fungals, they'll be back in fighting shape soon enough. Hydras would seem the answer, but they're considerably less mobile than Mutalisks and die to them without Infestor support or critical mass, assuming the Muta flock has reached a large size.
This new Muta vs Muta ZvZ is compared during nearly every professional cast to “Brood War ZvZ,” in which players traded early game build orders into a fast Spire nearly every game. However, Muta vs Muta in Brood War isn't even comparable to its counterpart in StarCraft II – the unit interactions have almost nothing in common, thanks to two key differences. First, Mutalisks were more microable in Brood War, thanks to the ability to shoot while changing direction (see this example) – Lee Jaedong made his career in part off of having the greatest Muta control in the world, making him unbeatable in ZvZ. But when asked about his favorite SC2 unit? “The mutalisk is very commonly used in Brood War but I feel sad that it is impossible to control mutalisks the way I did in Brood War.”
Second, and most important, the Zerg air-to-air unit was a much more interesting unit than the Corruptor. The Scourge was effectively an air-to-air Baneling which you produced two at a time directly from your larva. A single cheap, speedy Scourge could nearly kill a Mutalisk on its own. As a result, “Muta vs Muta ZvZ” consisted of players producing the proper ratio of Mutalisks and Scourge and knife-fighting with careful control – much like early game Ling/Bane in SC2, one mistake could end your entire game. The existence of Scourge and Muta micro (plus the limited control groups) prevented Zerg players from building up these gigantic, unkillable Muta flocks of 30+ as their opponent could attack at any time if they had confidence in their micro.
This isn't to say that the game needs to be Brood War. There are plenty of ways to make SC2's ZvZ more interesting without copying the previous game (though Scourge would also provide a great answer to Medivac Boost and Skytoss, I must say), but this balance patch isn't it. It's not a bad change by any means. In fact, I applaud Blizzard for their restraint in only making a small, targeted change. But it will likely turn out to just be a Band-Aid. What will eventually move players away from the current Muta vs Muta trend won't be an extra bit of damage on Spores, but meta and maps. The game's only been out for a month, so there's no reason to think that this current trend is unbreakable. Someone will get sick of Muta vs Muta and come up with something.
But as long as we're stuck on this style, we're in for some dull games. Without something like micro and Scourge to spice it up, Muta vs. Muta is the worst kind of “deathball” syndrome. With so little air-based micro, perhaps a change to the ground units would be warranted. But the problem there is that a buff to solve problems in a mirror matchup could have unpredictable repercussions on ZvP and ZvT. It all depends on where Blizzard wants to take the game. And maybe they're fine with it, and believe the game will move away from that style in time.
In the meantime, I just hope we see more ling/bane knife fighting and less long Muta stalemate. I'll take tense five minute games over boring twenty minute games any day of the week. Because ling/bane got it right. Micro, tension, knife's edge between life and death. That's what Muta vs Muta used to be. And it was awesome.