Riley O'Brien, a half-Korean reliever for the St. Louis Cardinals set to pitch for South Korea at the World Baseball Classic (WBC), has sustained a calf injury. The 31-year-old was named the team's closer. This marks another setback for South Korea's pitching staff.
Riley O'Brien, a half-Korean reliever for the St. Louis Cardinals, sustained a mild right calf strain during a live bullpen session on Saturday at the team's spring training site in Jupiter, Florida. According to MLB.com, the right-hander has not thrown off a mound since Monday. "It felt better today than it did yesterday," O'Brien said on Tuesday (U.S. local time). "Hopefully, it's nothing too long-term."
The World Baseball Classic (WBC) begins on March 5 in Tokyo, with South Korea scheduled to play tuneup games in Osaka in the preceding days. O'Brien's availability for the national team is now in jeopardy. Under WBC eligibility rules, players can represent the country of birth of one of their parents, even if they were not born there themselves. South Korea selected four U.S.-born players of Korean descent this time, including O'Brien, Detroit Tigers outfielder Jahmai Jones, Seattle Mariners pitcher Dane Dunning, and Houston Astros utility player Shay Whitcomb.
Manager Ryu Ji-hyun had named the 31-year-old O'Brien as South Korea's closer, assigning him to high-leverage spots from the seventh to ninth innings. In 2025, O'Brien posted a career-best 2.06 ERA over 42 games with six saves for the Cardinals.
If O'Brien cannot pitch, Ryu will need to select from a pool of All-Star closers in the Korea Baseball Organization (KBO), such as KT Wiz's Park Yeong-hyun, SSG Landers' Jo Byeong-hyeon, and LG Twins' You Young-chan. Former Twins closer Go Woo-suk, who signed a minor league deal with Detroit in December, is also a candidate for ninth-inning duties. South Korea is already without two key starters: Hanwha Eagles' Moon Dong-ju due to a shoulder injury and Samsung Lions' Won Tae-in, cut on Sunday for elbow issues.
