Alex Cora, in his first season as Red Sox manager,  celebrates Boston's clinching win at the 2018 World Series.
CNN  — 

The 2018 Boston Red Sox illegally used a video replay room during regular-season games to decipher the signs of opposing catchers, three unnamed sources who were with the franchise that year told The Athletic.

The Red Sox won an amazing 108 games during the regular season and lost only three playoff games in winning a World Series title.

Officials at Major League Baseball said Tuesday they will investigate the matter. Red Sox officials said the accusations are new to them.

“We were recently made aware of allegations suggesting the inappropriate use of our video replay room. We take these allegations seriously and will fully cooperate with MLB as they investigate the matter,” the Red Sox said in a statement.

The replay room is where staff members watch the game and can point out plays for the team’s manager to challenge.

The system worked like this, according to The Athletic: A staff member in the Red Sox’s video replay room would relay the catcher sign sequence through a player who visited the room. A person in the dugout would relay the information to a baserunner who could see the signs as the catcher signaled the pitcher.

The runner used a method to tip the batter that he knew what pitch was coming.

“Put two feet on the bag or look out into center field, and do something that’s subtle,” a source told The Athletic. The batter watched as the runner stepped off the base and learned the pitch through which of his teammate’s feet left the bag first, the publication reported.

During the regular season, the Red Sox led the league in runs scored, batting average, batting average with runners in scoring position and several other statistical categories.

The Athletic reported its sources are “bothered by a subculture of in-game electronic sign stealing.”

“It’s cheating,” one source said. “Because if you’re using a camera to zoom in on the crotch of the catcher, to break down the sign system, and then take that information and give it out to the runner, then he doesn’t have to steal it.”

The sources said that because opponents changed signs so frequently in the postseason, the system “did not appear to be effective or even viable (for playoff games),” The Atlantic reported. In addition, MLB reportedly added their own observers in replay rooms during the playoffs.

This is not the first time the Boston Red Sox have been investigated for alleged sign stealing. During the 2017 season, the Red Sox were fined by MLB for using an Apple Watch to relay stolen signs to hitters in games against the New York Yankees. While the practice of sign stealing is not explicitly banned in baseball, using technology to do so is prohibited.

The 2017 World Series champion Houston Astros are being investigated by MLB for allegedly using video technology to steal signs during their championship season. Alex Cora, who managed the Red Sox during their 2018 championship run, served as bench coach for the Astros in 2017.

Major League Baseball told CNN Sports: “The Commissioner made clear in a September 15, 2017, memorandum to clubs how seriously he would take any future violation of the regulations regarding use of electronic equipment or the inappropriate use of the video replay room.”