Who will close games for the 2026 Cardinals?

The St. Louis Cardinals roster is set for Opening Day. Matthew Liberatore will kick things off for the starting rotation, and the rest of the starters will follow in suit. Although the fans know their first starter, the roster construction, and now know that top prospect JJ Wetherholt made the cut, what they don’t know has been otherwise certain in recent years. 

Late Game Questions?

The ninth inning is up for grabs in The Lou. After a slew of high-upside arms rotating in and out, St. Louis had found their lockdown arm for the last three outs in Ryan Helsley. In 2025, Helsley was dealt to the Mets at the deadline and signed with the Orioles ahead of the 2026 season. Now, the Cardinals have uncertainty in a key role for the first time since Alex Reyes struggled with injuries in 2022. 

2025's Best

The most obvious choice is 2025 breakout arm Matt Svanson. The right-hander put up astounding numbers and had the underlying metrics to vindicate every ounce of success. Svanson was elite at inducing strikeouts and also averaged 96.8mph on his fastball. Velocity is often non-negotiable in the ninth, and Svanson isn’t trying to barter. If he wants to maintain the success he saw in 2025, he’ll have to improve his chase rates. 

It’s characteristic of MLB hitters to shrink the zone and get chippy when the game is on the line. This often nipped at Helsley during his tenure in St. Louis. When you don’t fool anyone, and hitters aren’t trying to do damage but rather just get on base, base hits can come in bunches. Svanson was excellent at everything other than racking up chase. In 2026, if he can get hitters to expand, he’ll take the next step to being a household backend arm. 

Southpaw Supremacy

Another candidate that fans have been clamoring for is left-hander JoJo Romero. 2025 saw new highs for the former Philly, a 2.07 ERA and eight saves from a setup man play on any roster. I’d caution the Redbird fans who chant for Romero’s name to be called consistently in the ninth. He was fairly successful against both righties and lefties, so the splits aren’t daunting, but the underlying data suggests he could run into trouble as a full-time closer. 

Ball four mocked Romero at times in 2025, and similarly to Svanson, he struggles to garner any chase. If he were to supply a role similar to prime Giovanny Gallegos, where he’s platooned into the ninth and the Cardinals pick and choose spots that promote his success, Romero should soar. If he’s forced into a role that he might not be suited for, it could tank the trade value of what looks to be one of the Cardinals' more valuable assets come July. Be careful with Romero. In Philly, he was buried treasure; now, X might not mark the spot in the ninth. 

High Velo -> High Upside

Riley O’Brien is the last headlining candidate to close for the Cardinals in 2026. O’Brien has the most explosive stuff out of the top three arms in the pen. Romero fools hitters with a UFO-like sweeper and occasionally turns over a changeup to righties. Svanson mimics the Jordan Hicks sinker and rips off a cutter to employ movement that crosses both sides of the plate. O’Brien simply overpowers and can still spin it.

In 2025, his fastball averaged 98mph in 42 innings, and he had a 90th-percentile extension. When a pitcher has good extension, it creates perceived velocity by a hitter, but O’Brien already throws triple digits. That combination could be DEADLY. The Cardinals should give O’Brien every opportunity to man the ninth as his ceiling clearly sits the highest of any arm the Cardinals are deploying from the pen in 2026. 

Ryan Helsley was a dominant arm for the Birds on the Bat. As a Cardinal, he broke St. Louis’ single-season saves record and brought calmness to the latter innings. The Redbirds might not be able to replicate his success immediately, but they have some really intriguing arms to start thumbing through.