Inside The Cardinals

Cardinals 2025 Breakout Star At Risk Of Injured List Stint

The Cardinals hurler has an injury question mark...
Patrick McAvoy|
Sep 5, 2023; Atlanta, Georgia, USA; A detailed view of the hat and glove of St. Louis Cardinals second baseman Nolan Gorman (not pictured) before a game against the Atlanta Braves at Truist Park. Mandatory Credit: Brett Davis-Imagn Images
Sep 5, 2023; Atlanta, Georgia, USA; A detailed view of the hat and glove of St. Louis Cardinals second baseman Nolan Gorman (not pictured) before a game against the Atlanta Braves at Truist Park. Mandatory Credit: Brett Davis-Imagn Images | Brett Davis-Imagn Images

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St. Louis Cardinals

The St. Louis Cardinals traded three relievers away ahead of the 2025 Major League Baseball trade deadline including Ryan Helsley, Steven Matz, and Phil Maton.

While this is the case, the Cardinals still have the sixth-best bullpen ERA in baseball at 3.61. Part of the reason why this is the case is because of the performance of Riley O'Brien this season. Before the 2025 season, O'Brien had made just 10 appearances in the majors over the course of three seasons. This year, O'Brien has made 31 appearances for the Cardinals and has responded with an eye-popping 1.69 ERA and 35-to-17 strikeout-to-walk ratio in 37 1/3 innings pitched.

O'Brien has been one of the Cardinals' biggest breakout players this season, but there's a chance the club could lose him to the Injured List due to shoulder fatigue, per Derrick Goold of the St. Louis Post-Dispatch.

Will the Cardinals see the hurler again this season?

St. Louis Cardinals relief pitcher Riley O'Brien
Aug 8, 2025; St. Louis, Missouri, USA; St. Louis Cardinals relief pitcher Riley O'Brien (55) pitches against the Chicago Cubs during the ninth inning at Busch Stadium. Mandatory Credit: Jeff Curry-Imagn Images | Jeff Curry-Imagn Images

"Riley O’Brien did not recover as quickly as hoped from his scoreless inning Thursday against the Pirates, and the Cardinals elected to give him the entire Reds series off," Goold said. "He continued to experience fatigue near his right shoulder Sunday and will undergo an exam Monday in St. Louis. The injured list has been discussed, and that will allow the Cardinals to promote two pitchers for the pitching staff Monday if O’Brien may miss another week or so.

"Right-hander Chris Roycroft is set to join the Cardinals. Other pitchers being considered for promotion as rosters expand or the month progresses are right-handers Roddery Munoz, Curtis Taylor or lefty Anthony Veneziano."

Right now, the Cardinals have just 24 games left in the regular season. An Injured List stint would at least come close to ending O'Brien's season at this point in the year. It's September now and there are just a few weeks left before the campaign comes to a close.

Expect to see an answer on O'Brien's status in the very near future and potentially as soon as Monday. As more information is provided, it will be shared.

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Patrick McAvoy
PATRICK MCAVOY

Patrick McAvoy's experiences include local and national sports coverage at the New England Sports Network with a focus on baseball and basketball. Outside of journalism, Patrick also is pursuing an MBA at Brandeis University. After quickly rising as one of the most productive writers on the site, he expanded his reach to write for Baseball Essential, a national baseball site in Sports Illustrated Media Group. For all business/marketing inquiries regarding Inside The Cardinals, please reach out to Scott Neville: nevilles@merrimack.edu

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