9:35 AM PT -- According to Walker Buehler's reps, the incident actually took place back on Sept. 27 -- while he and a few of his teammates stayed home from the Dodgers' series with Colorado to prep for the postseason.

Buehler's reps say the pitcher and his wife, McKenzie, were attending the races at Santa Anita Park, when he was "unknowingly the victim of a snatch and grab robbery of his watch."

"The incident was reported to police and is currently under investigation," Buehler's reps said in a statement. "We are grateful Walker and McKenzie were not harmed and Walker is focused on the playoffs."

Cops, meanwhile, told TMZ Sports on Tuesday morning there were actually three incidences of grand theft at the track that day. They did not name the victims in the cases -- although they did say one arrest was made.

The start of the Dodgers' playoff run has been anything but smooth for Walker Buehler ... not only is L.A. just 1-1 so far, the star's pricey watch was reportedly lifted off his wrist during a robbery at a local race track.

According to ABC7 -- Buehler was at Santa Anita Park in Arcadia at some point over the weekend when the heist occurred.

The outlet states after a mob of people surrounded the pitcher and his wife -- someone unbuttoned his shirt sleeve and nabbed his timepiece. Reportedly, the wristwear was valued at around $100,000.

Cops have not yet commented on the matter -- we reached out Tuesday morning, but have yet to hear back.

As for the Dodgers, the team told ABC7 it had no statement on the incident.

Buehler -- a Kentucky native who grew up a fan of horse racing -- is slated to start Game 3 of the Dodgers vs. Padres playoff series on Tuesday in San Diego ... and it'll be a huge tilt for the team.

Even though they won Game 1 -- the Dodgers were blown out in Game 2 ... and both matchups were contentious, to say the least.