The St. Louis Cardinals have placed their breakout reliever, Riley O’Brien, on the injured list and shut him down indefinitely due to shoulder fatigue. The decision followed an MRI that confirmed his injury, prompting team officials to halt his activity “until a clear course of action is set.
O’Brien, a 30‑year‑old right‑hander, has been one of the most reliable arms in St. Louis’s bullpen this season. Through 31 appearances, he has posted a minuscule 1.69 ERA and a 1.13 WHIP, with 35 strikeouts across 37 1/3 innings, making this a significant blow to the Cardinals’ late‑inning strategy.
The timing couldn’t be worse. As of September 1, 2025, the Cardinals sit with a 68‑70 record and are battling for a Wild Card spot, while trailing their division rival Milwaukee Brewers by 17 games in the NL Central. Losing O’Brien further complicates their already difficult push for the postseason.
Riley O’Brien’s absence leaves a critical void in high‑leverage situations, especially given the team’s recent bullpen struggles. His shutdown underscores not only the urgency for reinforcements but also the delicate balancing act teams face with fragile breakout arms—where one misstep could derail both player health and team momentum.
Moving forward, the Cardinals will need to adjust their bullpen usage, possibly relying more on emerging arms or reshuffled roles among relievers. With the season entering its final stretch, every available arm—and smart management of those arms—could determine whether the Cardinals remain in contention.
