And, like many AIs, it can have "jagged capability" gaps, with inhuman failure modes living in them - which humans can learn to exploit, but the robot wouldn't adapt to their exploitation because it doesn't learn continuously. Happened with various types of ML AIs designed to fight humans.
For now. It's a work in progress.
I wonder how much practice these players had against the machine in the weeks leading up to the actual game. That would be significant to ensure they are playing at their pro level.
Rui Takenaka, an elite-level player who has won and lost matches against Ace, said in comments provided by Sony AI: "When it came to my serve, if I used a serve with complex spin, Ace also returned the ball with complex spin, which made it difficult for me. But when I used a simple serve - what we call a knuckle serve - Ace returned a simpler ball. That made it easier for me to attack on the third shot, and I think that was the key reason why I was able to win."
It seems like the human players might be playing in a way that tacitly overestimates their AI opponents' intelligence and underestimates their skill. AFAIK the SOTA Go AIs are still vulnerable to certain very stupid adversarial strategies that wouldn't fool an amateur (albeit they're not something you'd come up with in normal play, more like a weird cheat code). I wonder if this could get ironed out with a bit more training against humans vs. simulation.Humans use every clue they can get to predict the trajectory as early as possible. For example most players use a roughly similar technique for a certain stroke, e.g. the forehand topspin. They also tend to have a pretty narrow angle that they usually play it, relative to their body and their movement. Players use that predict where the ball will move, and position themselves accordingly. And they start that movement before their opponent has touched the ball.
Some players can deceive others by bending their wrist right before ball contact, which sends the ball in an unexpected direction (but that usually comes at the cost of an increased risk of missing the shot).
Similarly, the size of the stroke limits the pace (and spin) you can apply to the ball; when the opponent starts a short stroke, you can be sure the shot won't be fastest, and move closer to the table.
As I mentioned in a previous comment, it would be important to know how many weeks of preparation and training against this sort of robot the player had before the match.