I will start off by saying that I played Toss and Terran in BW and play Toss and Zerg in SC2. Also I have watched a lot of StarCraft over the years.
Protoss issues:
- Zealots are countered by every Zerg unit in the game cost for cost. Yes to zerglings on even upgrades. And even if you get an upgrade advantage, banelings will absolutely wreck you. In small numbers they can fight roaches but lose super badly in bigger fights. Much worse than the math from BW for Zealot vs Hydra. Protoss has to build Zealots because there is no other mineral dump but can at least use them for harass and thatâs what pros have resorted too. Using mineral dump (Zealots and prism) for harass. Gas units are to survive.
- Stalkers are literally countered by every early game Zerg unit in the game cost for cost. Only trade I can think of where Stalkers might do OK is Blink Stalkers vs slow roaches off creep. Zealots are pretty bad in PvZ but Stalkers are just god awful.
- Sentryâs are extremely expensive and fragile. They are powerful, but require more micro than it takes to defend against them. In PvZ, Ravagers have made them nearly obsolete and at this point in the meta, any decent level Zerg knows how to bait out FF and just drain their energy. Not a good unit to base balance on and has always been a bad unit for game design.
- Protoss late game air is completely unviable.
- Protoss has no early game map control. The only unit that Toss has that can gain map control is the oracle. Hence, 3(!) oracle openings. Arguably phoenix but Oracle is better for reasons stated below.
- Related to the above: There is no way for Protoss to stop Zerg creep.
- Zerg gets their third at ~2:30 or earlier which Protoss cannot keep up with.
- To even have have a chance at taking your third at a decent time you must have an oracle to deter/kill lings from killing the Nexus or potentially even wiping out your ground army (related: lings are cost efficiently against all early game Toss units)
- Oracle is really important but was nerfed into the ground.
- Immortal and Prism were nerfed.
- Colossus was nerfed (compared to pre LotV)
- HTs were nerfed multiple times.
- Spores require just a spawning pool. A necessity for TvZ but pretty much removes any harass potential for Toss, especially with 8 AA range queen.
- Many of these issues existed in Brood War (which was also favored Zerg in PvZ) but to make up for it, Toss had commensurately strong late game units and Zerg could be effectively pressured early game because of larva scarcity. Neither of these mechanics exist in SC2 to temper early game and late game PvZ.
There is more but those are the important ones.
Zerg issues:
- The only time Zerg is vulnerable is mid game. Early game they have full map control and excellent scout denial. Late game they almost without fail have more resources and an army that is superior (and, counterintuitively more expensive⌠for example, corrupters and banelings are probably the two most supply efficient and costly per supply units in the game⌠Banelings for sure)
- Zergs early game all ins are hard to scout and extremely hard to hold even at the highest pro level (see: Rogue showing the world just how scary a simple baneling/ling bust is vs Zest) Big disparity in difficulty to hold the all in vice the difficulty to execute
- Ravagers are expensive but they are a tier 1 unit useful in all match ups for the entire game. I love how people talk about queens and broodlords but nobody bats an eye when Serral or Dark are using Ravagers 20+ minutes into games and winning. Funny enough I think they are actually even better TvZ than PvZ especially when you have somebody skilled with them. Ravagers are micro intensive so really only are problematic at the highest skill levels. Ravagers biggest issue IMO is the very short bile cooldown. Pros can dish out insane damage and have insane ability to control enemy army movement with biles.
- Nydus play is still disproportionately hard to stop. If you miss the first Nydus, just get ready to slowly die because your low DPS units will never stop the waves of locusts.
- The Viper is arguably the best caster in the game.
- On the positive side, Infestor brood lord seems to finally be (mostly?) dead