The Cardinals placed right-hander Riley O’Brien on the 15-day injured list, as O’Brien is dealing with a flexor strain in his right forearm. Left-hander John King was called up from Triple-A in the corresponding transaction.
The ominous-sounding nature of the injury suggests that O’Brien could be in danger of a season-threatening surgery. Even if the strain can be managed with just rest and a normal rehab schedule rather than any kind of procedure, O’Brien is still likely looking at an absence of well beyond the 15-day minimum. The righty has made one appearance this season, tossing an inning of relief in the Cardinals’ season-opening 7-1 loss to the Dodgers.
O’Brien has now made exactly one appearance in each of his three MLB seasons, counting his previous cups of coffee with the Reds in 2021 and Mariners in 2022. An eighth-round pick for the Rays in the 2017 draft, O’Brien spent much of his minor league career as a starter before turning to full-time bullpen work in 2022. With an ugly 7.03 ERA over 39 2/3 Triple-A innings in 2022, the transition wasn’t exactly smooth for O’Brien, yet he significantly turned things around with Seattle’s Triple-A affiliate last season. The right-hander posted a 2.29 ERA, 57.1% grounder rate, and a 37.7% strikeout rate in 55 innings in Tacoma, and only a 13.6% walk rate marred that otherwise sterling performance.
The Mariners weren’t moved enough to give O’Brien any time on the active roster last year, and they ended up trading him to St. Louis in early November for just cash considerations. A minuscule 0.90 ERA over 10 Spring Training innings helped O’Brien win a spot on the Cardinals’ Opening Day roster, but it will likely be some time before he is able to return to the mound.