Fruitseller (Cool) may change his race in GSL #2 - Page 42

Key factors why Zerg is underpowered:
- Zerg cannot wall-in (even if you wasted resources for a row of spines the lack of ranged damage dealers to back up your wall makes it totally unviable.)
- Zerg can't fight in chokes (again the lack of ranged damage dealers means chokes are zergs natural enemy, and without something like the defiler to help with that it amplifys the problem.)
- Creep is a disadvantage (fighting off creep is a big disadvantage to Zerg, it also takes significant time and APM to spread creep, yet it can be destroyed very easily by the opponent. It is also a limiter on where you can build and also makes you very easily scouted)
- Zerg AA is weak (Hydras come late leaving Z open to abuse. Hydras are slow off creep and are made of paper. Spore crawlers are not effective and uproot takes too long and is a poor tradeoff, would rather a permanant spore with better range/dmg.)
- Zerg has less combat units, thus less options (Foregoing all workers, overlord/overseer/nydus for Z and observer / warp prism for P, because they are non combat and cant deal damage. The number combat units per race - T 12, P 12, Z 9 [10 if queen is counted])
- Zerg units lack utility without upgrades (e.g. zergling without speed upgrade, roach without speed or burrow, bane without speed, hydra without range, ultra without carapace. In contrast, marine/marauder/reaper/ghost/hellion/medivac/ still good with no upgrades, upgrades are just icing on the cake for terran)
- Zerg t3 takes too long to reach (From the instant you make your first Spawning Pool, it takes 410 seconds minimum before you can start making an Ultralisk, assuming you go Straight for it, or 480 for Broodlords. Compared to the 235 for a Battlecruiser, or 260 for Carriers/Mothership, that's obscene. source)
- Zerg does not have a unit that can deal damage from stealth (burrow)
- Zerg does not have a unit that can use the cliff jump mechanic
- Spawn larva is a blessing and a curse (Being able to bank larvae is great, but at the cost of having more APM required, requires queens which consume 2 supply ea. It is really more of a necessity than anything else, having units that are disposable and swarmy. Overall the mechanic is a disadvantage, macro is much easier from warpgates or rax/factories etc.)
- Zerg scouting can easily be denied
- Zerg units do not work well in 'critical mass', or as a ball. (Compared to T and P armies, Zerg has a weak army in critical mass, both T and P can get huge momentum going once they reach their critical mass. Zergs suffers from lack of good ranged damage and weak units. Choked terrain compounds this problem.)
- Zerg can be punished for mistakes very easily. (Mainly due to lack of ability to wall-in or to use chokes defensively)
- Corrupters and Infestors are less than good. (Even though fungal is decent, they're just not good units overall.)