Alex Cora was bench coach for the 2017 Houston Astros and manager of the 2018 Boston Red Sox. Both teams are under investigation by Major League Baseball for allegedly stealing opponents’ signs electronically. Charles Krupa/Associated Press

Major League Baseball says it will investigate allegations the Boston Red Sox illegally used their video replay room to steal signs between opposing pitchers and catchers during their 2018 championship season.

The claims were made Tuesday in a report by The Athletic. The website cited three anonymous sources it said were with the Red Sox during the 2018 season who said some players visited the replay room during games to get information on sign sequences.

Those sources told The Athletic that the Red Sox weren’t able to do it during the postseason because of in-person monitors used by MLB in those games.

“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. Given these allegations, MLB will commence an investigation into this matter,” the league said in a statement.

The Red Sox said they will cooperate as MLB looks into the allegations.

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

The illegal sign-stealing allegations are the second case against a recent World Series champion, as MLB continues to investigate the Houston Astros’ operation in 2017. Allegations in both cases implicate Red Sox Manager Alex Cora, who was a bench coach with the Astros in 2017 before joining the Red Sox in 2018. The Athletic had previously reported that Cora played a “key role” in devising the Astros’ system in 2017.

A Red Sox baserunner was required to convey the stolen signs to a batter, according to The Athletic. Here’s how the system allegedly worked:

A staff member in Boston’s video replay room would tell a player the sign sequence between the opposing pitcher and catcher. The player would return to the dugout, delivering the message on foot, rather than through a wearable device or a phone. Someone in the dugout would relay the information to the baserunner, leaving the runner with two easy steps: Watch the catcher’s signs and, with body movements, tell the hitter what’s coming.

In daily hitters’ meetings, Red Sox players and personnel would review their communication methods for that day. The runner would let the hitter know if he was aware of the sequence. “Put two feet on the bag or look out into center field, and do something that’s subtle,” as one Red Sox source described it. The runner stepping off the bag with the right foot first could mean fastball; left foot first, a breaking ball or off-speed pitch.

Such a system was far more difficult for opponents to detect than banging on a trash can, the technique allegedly used by Astros. It also had a semblance of propriety, incorporating old-school, legal practices: A runner on base still had to use his own eyes before he could put the contraband information to good use. Like many teams, the Red Sox often knew pitchers’ sequences heading into a game through the use of video. If a pitcher does not or did not change his sign sequence from his previous outing, that is and was his own responsibility. But if the sign sequences were altered on the fly, the Red Sox had a way to adjust almost immediately – by sending a player from the dugout to the video room a few feet away.

“It’s cheating,” a member of the 2018 Red Sox told The Athletic. “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.”

Sign stealing is not illegal in Major League Baseball unless it is done electronically.

Tuesday’s news comes on the heels of a report by ESPN’s Jeff Passan that indicates MLB Commissioner Rob Manfred could be close to handing out discipline in the Astros investigation in the next two weeks.

Astros General Manager Jeff Luhnow, Manager A.J. Hinch and other on-field coaches could face lengthy suspensions and the organization could be hit with record fines based on Manfred’s decision. According to Passan, players involved would not face fines or suspensions.

Cora could also fall under Manfred’s discipline. The Boston manager declined comment on Tuesday.

“I know you have a job to do and you have to ask the question, but out of respect for the investigation that MLB has and the Astros, I’m not going to answer the question,” Cora said.

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