It was the aftermath of Quintero making a "slanted eyes" gesture behind Chen, who is of Chinese descent, as the pitcher was being interviewed in the dugout by Fox TV's announcers during an Interleague game against the Pirates. The incident caused a backlash of indignation on Twitter and in the media.
Quintero apologized for the gesture in the clubhouse before the Royals' game against the Brewers on Tuesday night.
"I apologize to the fans and people who were offended from the bottom of my heart," Quintero said. "I really feel bad because people were offended. Me and Chen are good friends and we were joking around."
Quintero, from Venezuela, and Chen, from Panama, are Spanish-speaking friends. Chen's grandparents came from China to Panama during the building of the Panama Canal.
"I'm not actually offended at all," Chen said. "I'm proud of my heritage, being Asian, and I like the way my eyes look. I think it's a very good look for me ... it makes me look sexy."
Quintero said he apologized to Chen before Sunday's game.
"The next day I apologized to him and asked him if he was offended and he said no, but that he thought people, our fans and stuff, got offended," Quintero said. "I really apologize for what I did from the bottom of my heart and I don't want to do it again."