Aug 6, 2025; Los Angeles, California, USA; St. Louis Cardinals left fielder Lars Nootbaar (21) and relief pitcher Riley O'Brien (55) celebrate a win after defeating the Los Angeles Dodgers 5-3 at Dodger Stadium. Mandatory Credit: Kiyoshi Mio-Imagn Images Kiyoshi Mio-Imagn Images

Cardinals Hurler Turning Heads As Potential Ryan Helsley Replacement

Originally posted on St. Louis Cardinals on SI
By Zach Pressnell | Last updated Aug 11, 2025 9:00 PM ET

The St. Louis Cardinals seemingly waved the white flag at the trade deadline by trading a trio of expiring relief pitchers. They traded Phil Maton to the Texas Rangers, Steven Matz to the Boston Red Sox, and Ryan Helsley to the New York Mets.

While the losses of Maton and Matz hurt the team, it was the loss of Helsley that truly crushed the Cardinals' bullpen. Helsley had been one of the better closers in baseball for the last few years with the Cardinals.

But the team is already looking to replace Helsley's production at the end of games. There's a chance his long-term replacement is already in the Cardinals' organization.

Redbird Rants' Scott Plaza recently praised reliever Riley O'Brien for stepping up in the absence of Helsley. O'Brien has quietly been one of the best relievers on the roster for the last few weeks.

Riley O'Brien turning heads as breakout star in Cardinals' bullpen

Jeff Curry-Imagn Images

"Also encouraging is the fact that he has performed his best late in the game. In the eighth inning or later, he has thrown 13.2 innings, striking out 10 and allowing just two runs," Plaza wrote. "His command remains an issue at times, but he has shown improvement, only walking three batters over his last 6.2 innings, covering a span of seven appearances. While manager Oliver Marmol has yet to commit to one closer for the last push of the season, Riley O'Brien has to be near the top of the list for guys who can fill that role.

"JoJo Romero seemed likely to get some chances, but he is the only lefty in the bullpen, so he is still used in high-leverage matchup opportunities. If O'Brien can keep his momentum going through August, there's little reason to believe he won't become a favorite for the closer role in September and beyond."

O'Brien has been excellent this year. He has an electric arm with a wipeout slider. The Cardinals need this kind of production from him following the slew of moves at the deadline. Player like O'Brien are keeping the Cardinals afloat in the National League despite selling at the deadline.

But it's hard to picture him stepping in as the team's closer. He's already 30 years old and doesn't have the best big league track record. The Cardinals could hit free agency or the farm system to find their next closer, but O'Brien doesn't seem like the best option to replace Helsley.

This article first appeared on St. Louis Cardinals on SI and was syndicated with permission.

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