‘Yeah, That Happened.’ Joc Pederson Is Slapped Over Fantasy Football.

When fights occur in professional sports it can sometimes take years for the facts to come out. Rumors will swirl, tidbits will be attributed to anonymous sources and years later the people involved will finally explain what happened.

In the case of Friday’s slap heard around baseball, though, fans just had to wait for Joc Pederson to get to the clubhouse after the San Francisco Giants’ 5-1 loss to the Cincinnati Reds on Friday.

Pederson, an outfielder for the Giants, confirmed what social media had been buzzing about: Tommy Pham, an outfielder for the Reds, had slapped him before the game over a fantasy football transaction that Pederson says he made more than a year ago. No, really.

“Yeah, that happened,” Pederson said when asked directly about the slap.

The slap was part of an unusual series of events for the Giants. Earlier in the day, Manager Gabe Kapler wrote a blog post about gun violence and then announced he would not come to the field for the national anthem until further notice.

The slap occurred in left field just before the game, and led to a disagreement between the teams over whether Pham should be allowed to play. And in the eighth inning there was further confusion when Kapler called on reliever Jake McGee, only to be informed that McGee had mistakenly been left off that day’s lineup card, thus making him ineligible to play.

The violence between Pham and Pederson is not unheard-of in sports. Charles Oakley, a bruising N.B.A. player for several teams, has confirmed over the years that he struck a whole host of players, including the Hall of Famers Charles Barkley and Scottie Pippen — Pippen was Oakley’s teammate at the time — and he once attacked Tyrone Hill during shootaround over a gambling debt.

But Friday’s incident distinguished itself simply by the level of detail Pederson was willing to offer in its aftermath.

When asked what happened, Pederson explained that he and Pham participate in a fantasy football league together. More than a year ago, Pederson said there was a disagreement about a transaction he had made in which he moved a player who was listed as out to injured reserve. He said a text message sent to a group chat for the league accused him of cheating for “stashing” players on his bench. He did not say directly that Pham had sent the message.

“I looked up the rules and sent a screenshot of the rules, how it says when a player is ruled out you’re allowed to put them on the I.R., and that’s all I was doing,” Pederson said.

Pederson expressed confusion that Pham was upset about the move; he said that Pham had executed a similar transaction with his own roster, going as far as to offer who the player in question was with Pham’s team.

“It just so happened that he had a player, Jeff Wilson, who was out, and he had him on the I.R.,” Pederson said. “I said ‘you literally have the same thing on your bench.’”

Pederson said Friday’s incident did not have much lead-up. Pham approached him, asked if he remembered the issue, Pederson confirmed he did, and Pham slapped him across the cheek.

Pederson said he chose not to retaliate.

“I didn’t get emotional and I don’t think violence is the answer,” he said. “So I kind of left the situation.”

Pham was eventually pulled from Cincinnati’s starting lineup. He and Reds Manager David Bell declined to address the slap after the game, but Kapler, the Giants manager, said that the league would look into the incident.

“Major League Baseball is investigating it, and until that’s complete, I’m probably not going to say much on it,” Kapler said.