[push0ret]

They note that the robot achieved an "intermediate" skill level. This has been determined by letting it play matches against people of different skill levels as determined by a professional table tennis coach. The "Results" section explains this.

[repeekad]

Google had a very competitive employee ping pong league and one of the coaches was on the USA Olympic team, I doubt they would lie about ping pong skills

[eviks]

What do you think the mechanism is that would make them honest?

[yusina]

Just watch the videos. They don't support your statements.

[hooloovoo_zoo]

It looks very slow in the videos though.

[BugsJustFindMe]

But they don't explain what metrics they use to differentiate skill level other than waving the hands of a puppet coach. The arm control is great but they don't show it returning non-softballs. Is that what "intermediate" means?

[spongebobstoes]

Probably, if you consider that a beginner can rarely volley at all. At an intermediate level, a fast return pretty much just wins the point, when it doesn't hit the net or miss the table.