Answer: an Apple Watch
According to The New York Times, the New York Yankees filed an official complaint against the Boston Red Sox for stealing pitching signs during baseball games. Major League Baseball (MLB) conducted an official investigation that revealed the use of an Apple smartwatch by Red Sox training staff to message pitching signals to a trainer in the dugout. The trainer then delivered this information to players, who could use it while on second base — where they can see the signals their opponent’s catcher gives to his pitcher — to signal that information to their batter.
While sign-stealing in baseball is not against the rules, it is frowned upon, and the use of electronics or any equipment other than the eyes is not allowed. Technology has had a rough history with baseball, due to its ability to foster cheating techniques. Last year, MLB partnered with Apple to bring iPads into the dugouts, but the devices’ Internet capabilities were disabled so that coaching staff couldn’t use them to access any real-time feeds from the game. Smartphones are banned from dugouts and bullpens, but smartwatches are not, at least for now.