For every Bryce Harper, a highly touted phenom who became a household name as a teenager, there’s a Michael Petersen—a player who has to endure years of adversity and triumphs before finally getting his opportunity to shine on baseball’s biggest stage as the only British-born player in the MLB.

Now a Miami Marlins relief pitcher, Petersen’s journey to success wasn’t linear. It was a path of peaks and valleys, filled with setbacks and obstacles along the way.

Early Beginnings

Petersen, 32, was born in Middlesex, United Kingdom, on May 16, 1994. Although he was born in England, his parents, Randall and Maureen, relocated to California when he was one. It’s there that Petersen’s love for the game grew.

He came from two athletic parents, his dad being a former volleyball player and downhill skier, and his mom was a track star in her own right. Growing up in an athletic family, Petersen developed a love for sports. His father introduced him and his identical twin brother [Thomas] to baseball at a young age. They imagined themselves in the major leagues, practicing with wrapping paper balls and a cardboard bat.

He’d eventually play at St. Francis High School in Mountain View, California, where he became well known before being drafted in the 19th round out of high school in the 2012 MLB Draft.

Four Drafts, One Dream

Despite being drafted out of high school, Petersen’s journey was filled with challenges. He decided to forego signing with the Pirates. It wouldn’t be the first time. Petersen returned to play junior college at West Valley College in 2013 and Riverside City College in 2014 and 2015.

He’d get drafted in the 31st round by the Texas Rangers in 2013 and the 24th round by the San Francisco Giants in 2014. He declined to go pro both times. However, he finally decided to sign with the Milwaukee Brewers, who drafted him in the 17th round in 2015.

Earlier this season, Petersen was candid about why he kept declining the opportunities he was receiving.

“I just never got the opportunities I wanted,” Petersen told MLB Tonight. “Personally, I wanted to go to school. I enjoyed it.”

Roadblocks

Like almost anyone who’s become great at their craft, it doesn’t come without challenges. Petersen faced many challenges in the early part of his major league career.

Before making his major league debut, he played for nine different minor league teams, where he struggled with his pitching, starting with the Helena Brewers, where he posted an ERA of over 6.00 for back-to-back seasons in 2016 and 2017.

Just as he seemed to turn the corner, COVID hit. That was followed by Tommy John surgery in May 2021 and complicated shoulder issues that led to a near three-year stretch without competitive baseball. Petersen was trying to keep his emotions under control.

“There were some days where I was losing my mind,” Petersen told MLB.com back in 2023.

Finally Reaching The Majors

After recovering from Tommy John surgery, Petersen made a major comeback in 2023, playing for the Double-A Hartford Yard Goats and Triple-A Albuquerque Isotopes in the Colorado Rockies organization. Those appearances rebuilt his confidence for baseball’s biggest international stage.

That opportunity came during the 2023 World Baseball Classic, where Petersen represented Great Britain, the country where he was born.

That’s when everything changed.

After years of setbacks, including Tommy John surgery and shoulder issues that delayed his return, Petersen announced himself on the world stage with a 100 mph fastball that struck out All-Star third baseman Nolan Arenado of Team USA. It was the beginning of the resurgence.

He carried that momentum into 2024, playing for the Oklahoma City Dodgers in Triple-A as he began to round into form. He posted a 1.61 ERA with 31 strikeouts. Then his moment finally arrived—he was called up to the majors.

After more than a decade of multiple organizations and grueling setbacks, he made his official MLB debut for the Los Angeles Dodgers on June 18, 2024. 12 years in the making, a relentless pursuit officially becoming a reality.

He posted two strikeouts, one earned run, and one hit in two innings pitched in his first MLB win against the Rockies. However, he had another challenge ahead.

From Journeyman to Renaissance

Reaching the top is challenging enough, but staying in the major leagues is even tougher. After making his debut with the Dodgers, Petersen navigated the uncertainty of professional baseball in 2025, moving between the Toronto Blue Jays, Los Angeles Angels, Atlanta Braves, and Miami Marlins.

However, after overcoming the tribulations of Tommy John surgery, shoulder complications, and years of setbacks, Petersen remained undeterred. The persistence that carried him through the toughest moments of his career eventually paid off, as he established himself as a reliable relief option for the Marlins.

With Miami in the midst of the playoff race, Petersen has been a key contributor in the bullpen, posting a 2.84 ERA with 51 strikeouts over 44 innings pitched as of July 30.

After years of searching for a home, Petersen finally found one in Miami. The adversity and setbacks that tried to knock him down couldn’t overcome his unwavering belief in himself. Now, he is experiencing the career renaissance he spent years fighting to achieve.