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Rookie Reliever Rides Unorthodox Throwing Motion to Huge Success Out of Cardinals Bullpen
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- Rookie Reliever Rides Unorthodox Throwing Motion to Huge Success Out of Cardinals Bullpen
Roundtable Sports' John Denton breaks down Cooper Hjerpe's dominant four-inning relief appearance in his MLB debut on Sunday in Colorado .
All throughout Cooper's Hjerpe's baseball life, criticswere skeptical and doubtful of his unorthodox, herky-jerky throwing motion fromthe left side – one where he delivers pitches from a three-quarters arm angleand, at times, it appears as if his elbow is on the verge of dislocating.
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Even as Hjerpe piled up success at Woodland High School inNorthern California and then Oregon State University, many wondered about thestaying power of a delivery that seemed to put his arm, shoulder and elbow inawkward angles.
"Fortunately, he didn't listen to me all the time," CarlHjerpe, a former pitcher at Cal Poly University, said in a recent interview. "Ikept telling him, 'Get your arm up, get on top of the ball,' and he keptstaying low. So, I'm glad he didn't listen to me."
Hjerpe, whose professional career was interrupted by arthroscopicelbow surgery in 2022 and stopped completely by an ulnar collateral ligamenttear and Tommy John surgery that cost him all of 2025 and half of '26, finally gotthe chance to show off the power of conviction in his different throwing motionin his MLB debut on Sunday in Colorado. Baffling MLB hitters who clearly hadtrouble picking up the ball from his lower arm slot, the 25-year-old lefthanderpitched four perfect innings, struck out six in relief and nabbed his first MLBvictory.
A Cardinals team that trailed 5-1 at the time of Hjerpe'sentry into the game seemed to gain momentum from him retiring the Rockies inorder four straight times. The Cardinals scored six runs in the fifth inning toget him the lead, and then they effectively knocked him out of the game with alengthy three-run eighth inning to build a big lead before hanging on to win10-8.
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As it turns out, Hjerpe's success out of the bullpen in hisdebut was about as unique as his side-armed throwing motion. Hjerpe (1-0) authoredthe longest MLB relief outing in a debut without allowing a base runner since Arizona 's Max Kranick (five innings in 2021) St. Louis native Max Scherzer (4 1/3 inningsin 2008). Also, he became the first Cardinals reliever to debut with sixstrikeouts in relief since Marshall Bridges did it in 1959 against the Phillies .
"Honestly, once I got onto the field, I wasn't toonervous because that's when things got rolling," said Hjerpe, afirst-round draft pick in 2022 who had approximately 20 family members, friendsand former baseball teammates in the stands to watch his debut on Sunday."I was definitely locked in. The hardest part is like, between longinnings, staying locked in. I just sat on that bench and did whatever I couldto lock back in. Obviously, I was happy going four scoreless, and each inning Ijust got happier."
Clearly, the Rockies were none too happy trying to pick upthe baseball from the unorthodox-throwing left-hander. By design, the first twobatters Hjerpe faced were left-handers – Brett Sullivan and Vimael Machin – andthere were retired on a slow roller to short and the first strikeout of therookie's career. Originally, Hjerpe's 78.1 mph sweeper – one that featured 11inches of horizontal break, per Baseball Savant – was called a ball, but the callwas overturned when rookie catcher and former Triple-A teammate Leo Bernalrequested a challenge.
From there, Hjerpe's stuff only seemed to get nastier –even though he didn't throw a pitch harder than 92.2 mph during his fourinnings of work. In the fifth, he ended an eight-pitch at bat by striking outTroy Johnson with a 78.4 mph sweeper that featured 12 inches of horizontalbreak. In the sixth, he caught standout rookie TJ Rumfield looking with afour-seam fastball that broke 15 inches horizontally and he punched out MickeyMoniak with another fastball.
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With lefties 0 for 7 with four strikeouts against Hjerpe,the Rockies went to their bench for two right-handed batters in the seventhinning. All-Star Hunter Goodman managed an infield grounder off a changeup thatfeatured 15 inches of horizontal break and Connor Norby struck out on a sweeperthan broke in on his hands 13 inches. Hjerpe saved his hardest breaking pitchfor his final hitter, and he fanned Ezekiel Tovar with a filthy changeup thatcut away from the hitter some 17 inches, per Baseball Savant.
All of it, Hjerpe, was confirmation that sometimes an orthodoxthrowing motion can be a huge plus. Assuredly, he was tested along the way witharthroscopic elbow surgery in 2023, the Tommy John procedure in 2025 and the 15Minor League rehab starts he made this season prior to his MLB promotion, but hecame out on the other side of those hurdles stronger than ever.
"Everyone's journey is different," Hjerpe told MLB.com. "Minehad a lot of bumps in the road, man. Sometimes those things are out of yourcontrol.
