StarCraft II players will have a chance to prove that humans can beat a machine. You'll have to opt-in to matches against the AI, but once you do all the normal matchmaking rules apply - AlphaStar will just be another anonymous player on the ladder capable of playing any race, and your MMR will be affected as normal based on the results of the match.
Having been declared the divine overlord of Go and laid waste to thousands of Dota 2 players, our AI overlords are officially coming to conquer the StarCraft 2 ladder. Blizzard also ensures AlphaStar won't be learning from these matches so it can't improve during the period.
The experiment is a part of DeepMind's "ongoing scientific research into artificial intelligence", and the results will eventually be released in a peer-reviewed scientific paper.
The AlphaStar AI test will be opt-in, so you'll have to click the appropriate button on the in-game popup when it appears if you want an ass-kicking. If you ever change your mind, you can select the "DeepMind opt-in" button on the 1v1 menu.
The company has an FAQ with more information about the matches and how to join them. It's not a ideal record, and the folks behind Deepmind AI are looking to improve. The company then came up with a novel way to refine the AI further; it created a whole league of AlphaStar AIs, and had them all battle against each other. It will perceive the map using a "camera-like view" and won't have access to anything happening outside the visible map area. "All limits on AlphaStar's performance were designed in consultation with pro players", the company added.