I don't think so. It's quite easy to imagine that a computer would outperform humans in strategies that require precise execution and coordination in teamfights. In fact, it's not specific to OpenAI; even the built-in Dota bots' strengths are generally teamfight execution.

My guess is that if OpenAI 5 trained under a different hero pool, it would be weaker than it is now. It's very hard to predict how much weaker though.