Deepmind states in their released papers that they limit the actions per minute for the AI so it doesn't just win via speed. Their current approach is a bit simplistic and does not really reflect how humans perform actions but they want to keep it somewhat fair on the "mechanical" aspect of the game. OpenAIs Dota Agent also has similar restrictions although it has shown super human reactions in some cases. This should be tweakable in such a way that the Agent is on a human level and needs to actually be better at the decision making.