YORK, Pa.  — “Robot umpires” have arrived.

The independent Atlantic League became the first American professional baseball league to let a computer call balls and strikes Wednesday night at its All-Star Game. Plate umpire Brian deBrauwere wore an earpiece connected to an iPhone in his pocket and relayed the call upon receiving it from a TrackMan computer system that uses Doppler radar.

He crouched in his normal position behind the catcher and signaled balls and strikes.

“Until we can trust this system 100 percent, I still have to go back there with the intention of getting a pitch correct because if the system fails, it doesn’t pick a pitch up or if it registers a pitch that’s a foot-and-a-half off the plate as a strike, I have to be prepared to correct that,” deBrauwere said before the game.

It didn’t appear deBrauwere had any delay receiving the calls at first but players noticed a big difference.

“One time I already had caught the ball back from the catcher and he signaled strike,” said pitcher Daryl Thompson, who didn’t realize the technology was being used until after he disagreed with a call.