The right-hander stepped off the mound and said something to Mora, and he apparently continued his diatribe as he walked off the field at the end of the inning. Third-base coach Juan Samuel stepped between the two to calm Mora.
Nearly everyone involved in the incident explained their perspectives on Sunday. Only Beckett, who was approached shortly before Boston began stretching, was unavailable for comment.
"I think it was a situation where he thought that Melvin was relaying signs to the hitter," Samuel said. "Walking off the field, he made some comments and Melvin answered them, and I felt like if I didn't turn Melvin around and push him away, things could have gotten out of hand. He thought we were relaying signs, which I don't think we are."
"I've been playing for seven years straight against the Boston Red Sox, and that's never happened to me," added Mora. "[Beckett] came to me and apologized, because everybody over there knows me. I don't play that game."
Mora may or may not have been trying to get an edge, but stealing signs is an age-old baseball tradition that is still practiced in virtually every clubhouse -- though players generally don't admit it on the record. Pitchers often complain about it, but usually not when they're shutting out their opponent and dispatching batters with ease.
"He threw three breaking pitches to Ramon [Hernandez]," Mora said of the at-bat in question. "Hello? He didn't swing at that pitch, plus he hit and popped out. How can you steal signs thinking Ramon's going to hit one of the curves?"
"We don't play that kind of game," said manager Dave Trembley. "And if we did, we wouldn't make it that obvious. The way Beckett was throwing yesterday, I don't even think it would've mattered."
Boston catcher Jason Varitek said that none of Baltimore's swings would lead him to believe that the Orioles were stealing signs. He also said that he wasn't sure if Beckett was suspicious, but admitted that sign-stealing is still pervasive.
"There are some teams that are very renowned for doing it in our league," Varitek said. "Toronto is the most renowned for it. And New York. There are different teams throughout the league that are predictable, whether it's location or change of speeds. It's part of the game. But to defend against it, you have to use your coconut on the mound."
The good old days: Samuel said that stealing signs was more common when he played, and that payback was more severe. Players suspected of stealing signs would often be brushed back or hit outright the next time they came to the plate, but Samuel thinks that's changed with the familiarity between opponents.
"That's something you don't see a whole lot," he said. "I think with free agency [and] guys changing teams so much, there's more friendships. ... Every time I see one of our guys on base and I'm trying to get their attention to relay the sign, they're talking to somebody on the field. That's something I really don't understand, but that's the way it is today."
Retaliation may not happen as often, but the practice does. Samuel said that virtually every the time a pitcher steps off the rubber and a catcher comes to the mound, it's because they suspect somebody is taking their signs. Most of the time, it's a figment of their imaginations. But sometimes, they're exactly right.
"If you're not trying to get an edge, you're not trying," said Samuel, a three-time All-Star during his playing career. "I played on teams where we started relaying signs in Spring Training to get ready for the season. If you don't like it, change those signs. That's nothing unusual. [You'd] try whatever you could do to get an edge -- if you could get away with it."
Bruised and battered: Hernandez was hit in the head by a backswing by Manny Ramirez on Saturday and has battled several ailments this season, but Trembley said that his catcher is as healthy as can be expected. Hernandez, who missed the beginning of the season because of a strained oblique, has struggled to produce as well offensively as he has in seasons past.
"He's 100 percent. I just think he's been banged up all year," Trembley said of Hernandez, who got a day off Sunday. "I don't think he's really fully recovered from the oblique. He's been hit in the hand, the knee -- just the wear and tear of the tools of the trade. ... I think he's gotten in better shape by playing, and I think that was the best way to get him in shape.
"We caught him five games in a row -- I think that's the most he's played all year."
Quotable: "I've been playing 17 years of professional baseball, and I don't play that game. I don't like that, because I think that's cheating -- and I know the pitcher's got to eat, too." -- Mora, on sign-stealing
Coming up: The Orioles will start a three-game series in Yankee Stadium on Monday at 7:05 p.m. ET. The opener will pit Jeremy Guthrie against Chien-Ming Wang.
Spencer Fordin is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.