Seems like the key to beating an AI trained on how humans would play each other is to avoid anthropomorphising the AI, i.e try off the wall tactics that would obviously fail against a human opponent. See also the recent news about Marines sneaking up on a sentry bot by hiding under a cardboard box or dressing up as a tree.
https://media.hachyderm.io/media_attachments/files/109/892/231/130/393/773/original/1c1e460bde00a357.png