The Boston Red Sox used an Apple Watch to steal pitching signs from catchers in recent games against the New York Yankees, and potentially other teams, in an illicit ploy to gain an advantage for their hitters.

The Yankees caught Red Sox personnel stealing signs during a three-game series in Boston last month, reports The New York Times. Video of the scheme being carried out in the Red Sox dugout was included in a complaint filed with Major League Baseball, which examined the footage and confirmed the Yankees' suspicions.

According to people familiar with the inquiry, the video showed Red Sox assistant athletic trainer Jon Jochim looking at his Apple Watch, which presumably displayed text information about Yankees catcher signals, and passing those details on to team members including former Yankee outfielder Chris Young.

Stealing signs is allowed in baseball and players commonly observe catcher cues to the pitcher in order to determine what kind of throw is on the way. For example, a baserunner on second with a clear view of home plate can steal signs and pass the information along to a teammate up at bat, who can then better respond to the toss. The use of binoculars, electronic devices and other equipment as an sign stealing aid is strictly verboten.

In a normal — legal — scenario, team personnel viewing instant replays determine pitch signals and run gathered intelligence down to the dugout on foot. Trainers or other staff then relay that information to runners on base. That chain of events can be dramatically shortened through the use of text messaging and other digital technologies, though MLB rules prohibit such tactics.

When confronted by MLB investigators, the Red Sox admitted that trainers had been receiving signals from video replay personnel via Apple Watch for at least several weeks. Whether the strategy helped Boston reach its current spot at the top of the American League East is up for debate.

According to box stats compiled by The Times, the first Red Sox runner to reach second during the first of the games in question was Xander Bogaerts. Rafael Devers, who was at bat when Bogaerts was on base, hit a home run to give Boston a 2-0 lead. During that first game, the Red Sox went 5 for 8 with a man on second, the report said. Despite the strong initial showing, Boston went 1 for 6 in the second game and 3 for 10 in the third game.

In response to the investigation, the Red Sox filed their own complaint against the Yankees, saying the New York team steals signs in games using its YES television network.