[forax]

That's a cool idea but many games already struggle to find a fair balance point at all ranges of human skill, so expanding that range to include AI could just make things more difficult. Maybe there's a way to force the AI to replicate bad players, but I'm not sure what learning objective you would give it to achieve that.

[skwb]

I don't follow gaming balancing too closely, but I (naively) assume there's some reasonable analytical solution to find tuning. Like I would imagine if you're Blizzard and have logs of all the data, you could just regress race attack/defense/movement/etc. stats to find a potential equivalence point.

I suppose there's lots of interactions, but finding "well Zerg beats Protoss X% of the time", you could balance by messing slightly with resources or blanket buff.

[glun]

Starcraft is generally balanced by adjusting the map pool rather than the races.

[Etheryte]

I think achieving suboptimal play can be pretty straightforward — keep the parameters the same, but simply limit the amount learning. Some tweaks might be necessary here and there, but as long as you have basic gameplay down but not perfected, it should work pretty well.