[Laremere]

This was my read as well. It seems that Mana simply found a strategy that the AI had not found. Due to not having trained against it, the AI produced nonsense results. The commentators noted that the obvious response was to build a Pheonix and just completely shut down the harassment. The situation is similar to Alpha Go vs Lee Sedol match 4.

One of the hardest parts about these kinds of human vs ai expositions is making sure the AI has explored the full possibility space, so that can handle all situations. The techniques at play lack the ability to perceive a completely new situation and formulate a good response. (Though anyone who's lost to cheese in games they later learned easy counters for know that humans, while better than state of the art AI, aren't perfect here either.)