ST. LOUIS – The lowered stadium lights to garner attention of the home fans, rock music blaring from the speakers and a scoreboard seemingly erupting with flashing colors and lights are all perfectly in line with the modern way MLB teams introduce their closers these days.

It’s just that none of showy, flash and dash fits the mild-mannered, often painfully shy persona of Cardinals rising star Riley O’Brien.

Far too nice to ever object to anything Busch Stadium officials might do to try and inject excitement into the Busch Stadium crowd, O’Brien often enters games with his head down and a bit of embarrassment on his face as lights swirl from the scoreboard and music assaults the senses.

“Yeah, I notice it, but I’m already pretty fired up,” O’Brien deadpanned when mention was made of his rather loud entrance into game. “Yeah, that (flashing lights and loud music) is exactly who I am.”

O’Brien, 31, might be among the Cardinals, quietest and most mild-mannered players when it comes to his makeup away from the baseball field. But, between the white lines, his electrifying stuff and newfound confidence scream extrovert … and possibly future star.

How good has the 6-foot-4, rail-thin O’Brien been so far for the upstart Cardinals? In 10 outings that have covered 10 1/3 innings of work, he has yet to give up a run and he has averaged more than a strikeout an inning. Already, he’s 2-0 with five saves – numbers quickly approaching his best season totals – and foes are hitting a paltry .118 against him.

Then, there’s this: The Cardinals’ early-season bullpen troubles came largely because O’Brien missed two weeks of Spring Training with a calf strain and they brought him along slowly in late March and early April. Since he moved back into the role as the Cardinals’ top high-leverage reliever, O’Brien has been perfect in closing out games.

“It’s so nice to have the trust of the coaches and the trust for them to put me in those situations,” O’Brien said on Wednesday after pitching a perfect ninth to secure a series win for St. Louis against the Guardians. “I feel like pitching late in games and pitching in close games, that brings out the best in me.”

For O’Brien, it’s been quite the journey to get here. The Seattle native, who grew up going to Mariners games and dreaming of pitching in the big leagues, was picked in the eighth round of the 2017 MLB Draft by the Rays after starring at tiny University of Idaho. He didn’t reach the big leagues until 2021 – with the Reds – and his one appearance was a forgettable mess with three walks and two homers allowed. His second MLB season, this time with the hometown Mariners, also included a one-game cameo and he didn’t allow a run despite issuing another walk.

Dealt to St. Louis before the 2024 season, O’Brien made the Opening Day roster out of Spring Training and fanned Shohei Ohtani in his debut with the Cards. However, flexor tendon issues – often caused by the amount of torque he puts on his fribee-like sweeper – ruined that 2024 season.

O’Brien showed glimpses of his massive potential in 2025, and he moved into a primary closing role later in the season when the club dealt away star closer Ryan Helsley, setup man Phil Maton and swingman Steven Matz. In 42 outings of the 2025 season, O’Brien went 3-1 with a 2.06 ERA, six holds and six saves in nine opportunities.

“It’s so cool seeing him doing what he’s doing and the stuff coming out his hand is real,” manager Oliver Marmol said. “But it’s the mentality, demeanor and overall presence he has now to take things in stride and handle leverage has been impressive. … He’s done a phenomenal job.”

O’Brien has worked well in tandem with lefty reliever JoJo Romero, who also hasn’t given up an earned run this season. O’Brien admitted that he likely wouldn’t have been able to thrive in the closer’s role without the experience and momentum he gained last season when the Cardinals promoted him to the closer’s role following the trading of Helsley.

“That experience was huge and it allowed me to get into those situations to see how I would respond,” O’Brien said. “I had some good games last year, but there were others where I could have been a lot better. That’s helped me so much this year.

“For me, it all goes back to staying present. Whether I give yup a hit or not, I know that my stuff is good enough to be in the zone and there’s no reason to ever shy away. Just attacking guys and letting my stuff play has helped me so much.”

As for the flashy intro with the blaring music and strobe lights, O’Brien says he has no problems with it – even though it runs completely counter to his humble persona.

“They’re trending more in a modern direction with that and the fans enjoy it and it’s cool to hear their reactions when the lights go out,” O’Brien admitted. “But I’m usually pretty focused on the game and dialed in.”          

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