Riley O’Brien, the half-Korean pitcher for the St. Louis Cardinals, plans to pitch for South Korea at the World Baseball Classic in March, a report out of St. Louis said Saturday (local time).
Derrick Goold of the St. Louis Post-Dispatch said O’Brien, 30, accepted the invitation from the South Korean national team and is working on plans to travel to Japan, where South Korea will play all four opening-round games.
Riley O’Brien of the St. Louis Cardinals pitches against the San Francisco Giants during the clubs’ Major League Baseball regular-season game at Busch Stadium in St. Louis, in this Getty Images file photo from Oct. 8, 2025. (Yonhap)
The tournament goes from March 5 to 17.
Thanks to loose eligibility rules for the WBC, players can represent the country of birth of one of their parents, even if those players themselves weren’t born in that country. For the 2023 WBC, South Korea had Gold Glove-winning infielder Tommy Edman, who was born in the US to a Korean mother.
O’Brien was born to a Korean mother and has the Korean name Chun-young.
South Korea manager Ryu Ji-hyun said earlier this month he was hopeful about three to four US players of Korean descent would join his team for the WBC. While Edman has already been ruled out due to an offseason ankle surgery, South Korea, in addition to O’Brien, may also get the services of Detroit Tigers outfielder Jahmai Jones.
Seattle Mariners outfielder Rob Refsnyder, who was born in Korea but was adopted by an American family as an infant, is another candidate.
O’Brien was an eighth-round pick by the Tampa Bay Rays in the 2017 draft but made his big league debut with the Cincinnati Reds in 2021 following a trade in the previous year.
The Reds shipped him to the Mariners in April 2022, and O’Brien made one appearance with that club.
He joined the Cardinals in November 2023 and enjoyed his best big league campaign in 2025, when he pitched to a 2.06 ERA over career highs of 42 games and 48 innings, along with a 3-1 record and six saves.
He struck out 45 and walked 22. Per Baseball Savant, O’Brien threw his sinker over 48 percent of the time and slider about 30 percent of the time in 2025. The right-hander averaged 98 mph with his sinker and held opponents to a .228 batting average. O’Brien featured the curveball about 21 percent of the time last year, and opposing batters only hit .059 off that pitch.
The final WBC roster is due Feb. 3.
South Korea failed to get out of the first round at each of the past three WBCs after reaching the semifinals at the inaugural edition in 2006 and losing to Japan in the final in 2009.
Ryu took some 30 players, most of them from the Korea Baseball Organization, to Saipan to open a preliminary training camp in Saipan on Jan. 9, and they are scheduled to return home in two groups, Tuesday and Wednesday. The next training camp with the final WBC roster will be in Okinawa, Japan, starting Feb. 15.
It wasn’t immediately clear if O’Brien and other players based in the majors will be able to join the Okinawa camp, which will coincide with the start of their big league clubs’ spring training, or if they will travel to Japan in early March just before the tournament. (Yonhap)