Boston’s two passions—science and baseball—come together in a friendship between a Harvard medical student and a Red Sox pitcher.

Robin Orwant

It’s hard to imagine someone with a more exciting life than Matthew McCarthy. The Harvard medical student has played professional baseball, assisted in surgery at Massachusetts General Hospital, done research in a leading stem cell laboratory at Children’s Hospital Boston, and plunged a needle into the heart of an African bat to test for the Ebola virus. Who could top that?

Well, McCarthy’s close college friend, Craig Breslow, might. This past season, he fulfilled his childhood dream: pitching for the Boston Red Sox at Fenway Park. But he’s not your average ball player. Breslow, along with McCarthy, was a biochemistry undergraduate student at Yale University. And he has been known to hang out with McCarthy in lab when not on the field, nurturing his long-held aspirations to become a doctor.

Most people look back on their lives at some point and wonder where they might have ended up had they made different choices or possessed just a tiny bit more talent at something they loved doing. McCarthy and Breslow don’t have to wonder.

At a pivotal moment, each man came to the same fork in the road as smart, young professional baseball players, and each made a different decision. McCarthy chose the path to medical school and research, while Breslow stuck it out in baseball. Their enduring friendship gives each of them a rare opportunity to experience a little bit of life on the road not taken.

Common beginnings

Today, Breslow and McCarthy inhabit completely different worlds, but they share an eerily similar past. Both were left-handed pitchers in high school. Both were students in Yale’s molecular biophysics and biochemistry department. Both worked in the lab of Joan Steitz, a Howard Hughes investigator at Yale who does research on RNA processing. Both were on Yale’s baseball team. And both had the same dual dreams: playing professional baseball and practicing medicine.

Like many young boys, Breslow and McCarthy grew up dreaming of playing in the big leagues. They began to show real promise on the field in high school, but neither was willing to stake his career on baseball.

So they decided they couldn’t go wrong by accepting an offer of admission to Yale–a school strong in the life sciences with a top-notch baseball program. Once there, it was almost inevitable that these two young men who had so much in common would share a special bond.

“I met Craig my first day at Yale,” remembers McCarthy. “We were fast friends. We did everything together.”

Still, the two were different in some ways. Though they did well in their classes and planned to apply to medical school, McCarthy showed a greater interest and aptitude for scientific research and spent more than a year working on a project in Steitz’s lab. Breslow would later spend a few months in her lab as well, though he worked mainly as a technician assisting graduate students.

McCarthy “did a lovely job and made a substantial contribution” to a paper published in the EMBO Journal, says Steitz. “I predicted he would eventually make his mark in medicine rather than in baseball.”

By the time he graduated in 2002, though, McCarthy’s pitching was good enough to earn him a spot on a minor-league affiliate team of the Anaheim Angels. Breslow also got into the minor leagues, with a team affiliated with the Milwaukee Brewers.

Decision points

After struggling for a season, McCarthy realized he wasn’t meant for a career in professional baseball. Fortunately, when McCarthy was cut from his team in 2003, he had a pretty good backup plan—Harvard Medical School.

A year later, Breslow found himself in the same position when the Brewers cut him. “That was the first time I had to look myself in the mirror and ask myself whether I had a future in baseball,” says Breslow. Like McCarthy, Breslow had already been accepted to medical school. Yet, he wasn’t sure he wanted to give up on his pitching career.

After much soul-searching, and a few phone conversations with McCarthy, Breslow decided he wasn’t quite ready to exchange his uniform for scrubs. Breslow went back to his pitching coach at Yale, who arranged for him to try out for the New Jersey Jackals, a team in an independent league. The Jackals liked what they saw and signed him on.

Breslow got another shot at the big leagues in 2005, when he signed on with the San Diego Padres. Although he played mostly for a Padres’ minor-league affiliate team, he did get to pitch a few major league games for the first time when the Padres needed a left-handed relief pitcher.

This past season, Breslow signed on with the Red Sox. He spent most of the season pitching for the Sox’s minor-league team but was called up to play in 13 games for the Red Sox as a relief pitcher.

While this wasn’t the Sox’s best season, Breslow says it was still a thrill of a lifetime. “Playing in Fenway Park is something you dream about as a kid,” he says. “I’m never going to look back and wish I’d gone to med school a year earlier.”

Back to school

Meanwhile, in the fall of 2003, McCarthy started medical school. As his first year ended, and baseball season was getting underway, McCarthy knew he had to keep himself busy. “I realized I didn’t want to be around when the next baseball season came because that was going to be my first baseball season without me playing,” he says. “I wanted to get as far away from America and baseball as possible.”

So he spent a summer in Cameroon as a research assistant, catching African bats and testing them for the deadly Ebola virus. He discovered a passion for the study of infectious diseases. The following summer, he went to Malaysia for a similar research project. Soon, he’ll be off to South Africa to work in an AIDS clinic.

McCarthy’s research hasn’t always been in the field. Last year, he took a year off from medical school to work in Leonard Zon’s stem cell lab at Children’s Hospital.

Whatever McCarthy ends up doing with his career, he’s certain it won’t have anything to do with sports medicine. “It’s probably the last thing I would ever want to do,” he says. “I feel like sports medicine would be sort of hanging on to something.”

Unlike McCarthy, Breslow doesn’t feel the need to make a clean break with the past. In fact, he seems determined to keep the door open to medical school. He brings his biochemistry textbook and notes from Steitz’s class to spring training to stay sharp. And during the past season in Boston, he sometimes visited McCarthy in Zon’s lab and heard about McCarthy’s latest experiments.

Steitz is cautiously optimistic about Breslow’s intended career change. “At any age, Craig could certainly go to medical school and do beautifully,” she says. But if his professional baseball career continues for 10 or 15 years, she wonders whether Breslow will have the energy for the many grueling years of training required to become a doctor.

Despite having such different lifestyles, Breslow and McCarthy remain close. They talk on the phone several times a week, and during the baseball season, they get together often. While their future in baseball and research is still up in the air, they know one thing is certain—their friendship will endure.