St. Louis Cardinals pitcher Riley O’Brien throws live batting practice during a spring training baseball workout, Feb. 14, in Jupiter, Fla. AP-Yonhap
Riley O’Brien, half-Korean reliever for the St. Louis Cardinals set to pitch for South Korea at the upcoming World Baseball Classic (WBC), is dealing with a calf injury — the latest blow for the country already missing some key pitchers.
MLB.com reported Tuesday (U.S. local time) that O’Brien picked up what the player called a mild right calf strain during a live bullpen session on Saturday at the Cardinals’ spring training site in Jupiter, Florida. The right-hander has not thrown off a mound since, according to the report.
“It felt better today than it did yesterday,” O’Brien was quoted as saying on Tuesday. “Hopefully, it’s nothing too long-term.”
With the WBC starting on March 5 in Tokyo and South Korea scheduled to play tuneup games in Osaka in the days before that, O’Brien’s availability for the national team may be in jeopardy.
Under the WBC’s eligibility rules, players can represent the country of birth of one of their parents, even if those players themselves weren’t born in that country.
South Korea selected four U.S.-born players of Korean descent this time, with O’Brien joined by Detroit Tigers outfielder Jahmai Jones, Seattle Mariners pitcher Dane Dunning and Houston Astros utility player Shay Whitcomb.
Manager Ryu Ji-hyun has already named O’Brien as South Korea’s closer, saying the 31-year-old will pitch in high-leverage spots anywhere between the seventh and the ninth innings.
In 2025, O’Brien pitched to a career-best 2.06 ERA in 42 games while recording six saves for the Cardinals.
If O’Brien can’t pitch for South Korea, Ryu will have to choose from a pool of All-Star closers for Korea Baseball Organization (KBO) clubs, such as Park Yeong-hyun of the KT Wiz, Jo Byeong-hyeon of the SSG Landers and You Young-chan of the LG Twins. Former Twins closer Go Woo-suk, who signed a minor league contract with Detroit in December, is also a candidate for the ninth-inning duty.
South Korea is already down two key starting pitchers. Hanwha Eagles fireballer Moon Dong-ju was left off the team due to a shoulder injury, while Samsung Lions ace Won Tae-in was cut from the team on Sunday owing to elbow issues.