Steamhammer’s ZvP win rate
Steamhammer’s BASIL win rates by matchup surprised me:
| matchup | % |
|---|---|
| ZvT | 62% |
| ZvP | 60% |
| ZvZ | 61% |
What the what?!? The numbers are indistinguishable! That’s not what I expected at all! Steamhammer has always been worse at ZvP, and always by a wide margin. What happened? I went so far as to suspect a bug in BASIL and compared other bots to see if anything was glaringly suspicious, but no, nothing was obvious.
Here are the same matchups as played by Randomhammer, which plays zerg identically except for what it may have learned.
| matchup | % |
|---|---|
| ZvT | 63% |
| ZvP | 65% |
| ZvZ | 78% |
Randomhammer plays weaker opponents because it is lower ranked, so its zerg rates are higher. ZvZ stands out as much stronger, the other two are again virtually equal. Compare the rates from February this year, when ZvT and ZvZ were close and ZvP was waving to them from far below.
What changed in the last few months? Steamhammer or its BASIL opponents? I’m sure the higher ZvZ win rate for Randomhammer is due to fewer ZvZ games versus Monster and Crona. But the fact that Steamhammer and Randomhammer have similar ZvP rates despite facing a different mix of opponents suggests that the ZvP change is in Steamhammer, not in the opponents. New versions since February are Steamhammer 3.4.8 and 3.5. I looked back at the change lists and nothing stood out as clearly advantageous for ZvP. Maybe the change of AbsoluteMaxWorkers from 75 to 65 is good for ZvP? It seems plausible, compared to anything else I can think of. (When Steamhammer reaches that worker count, it goes into late game big-army macro mode.)
Bot performance is sometimes mysterious. Intuition does not always bite. Does anybody have a theory?
As an aside, the matchup win rates of adias (aka SAIDA) are amazingly similar: They varied from 69.17% to 69.62% when I checked. Was that achieved by intense optimization of the play? Is it an effect of the learning system?
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