When event organizers were reviewing the list of participants for last week’s annual U.S. Open of bowling, one name caught their attention.

No one from the United States Bowling Congress, which runs the national championship, had expected to see it. But no one in the bowling world, which converged on the Indiana-based event that serves as one of five majors in the sport, was surprised by the entrant either.

Mookie Betts — Encino, CA.

“He entered just like any of our other members would have,” said Chad Murphy, executive director of the USBC. “We didn’t really see him in the beginning as Mookie Betts, the baseball player. He was just a USBC member who was eligible to compete.”

By now, Betts’ bowling exploits are almost as well-known as his six Major League Baseball All-Star selections and two World Series championships.

Long before he picked up a bat, Betts learned to bowl, squatting down as a 3-year-old to push the ball with both hands before he was strong enough to hold it with one.

“Bowling was the first thing I started doing,” Betts, the Dodgers’ star right fielder, said. “I think that kind of gets missed. I was doing that before I was doing anything else. I just have never stopped.”

As his major league career took off, Betts’ reputation in bowling circles grew as well, thanks to a surprisingly strong track record in professional events highlighted by a 300 game in the 2017 World Series of Bowling.

“He fits in and gained acceptance because he takes bowling seriously,” Murphy said. “People who bowl for a living appreciate that.”

Even at the U.S. Open — where, after originally planning to enter at a qualifying stage, Betts was given an exemption into the main 108-man field — Betts held his own in the notoriously difficult tournament.

After the first of three days of competition, he ranked near the middle of the pack. And though he faded to a 98th-place finish over the final two rounds, “you can say he beat 10 pros,” Murphy pointed out. Betts had an average score of 185.83 in the tournament.

“Yeah, he finished 98th,” Murphy added. “But that means he was worthy of being in the field.”

The craft comes so second nature to Betts now, some in bowling expect he could become a full-time pro whenever his baseball career ends.

“It wouldn’t surprise me,” Murphy said. “Because I’ve seen him get better since he’s been bowling these events the last few years. So when he actually does have time to dedicate more time and energy into it, I think he’s gonna just keep getting better.”

In the meantime, though, the hobby fills another important role for a player facing renewed expectations at his day job.

After their 111-win season ended in a postseason fizzle against the San Diego Padres last year, the Dodgers will begin spring training next week in Arizona in a state of transition. Their lineup lost All-Star Trea Turner in free agency. Their clubhouse has to replace a long-time leader in Justin Turner.

While the team is hoping to compensate through a string of offseason additions and up-and-coming class of farm-system talent, it will still largely be up to such returning cornerstones as Betts and Freddie Freeman to pick up the slack.

“It’s an opportunity for guys like Freddie and Mookie to step up with their voices,” manager Dave Roberts said last weekend. “And not only lead by example, but if there’s something that needs to be said, they’ve earned that right.”

So, ahead of a crucial season for both him and the club, Betts spent much of his offseason the way he typically does: giving his mind a rest from baseball by focusing on bowling.

“It’s like his second home,” Betts’ wife, Brianna, said jokingly. “You can find him there before you find him at the house.”

Said his mother (and fellow lifelong bowler), Diana Collins: “It’s been embedded in him since he was born.”

And even a little before then, actually.

“The night before I had him, I was bowling,” Collins recalled with a laugh. “He’s got bowling in his veins.”

Bowling featured prominently in Betts’ childhood. He was a standout on his high school team in Nashville. He was named the Tennessee boys bowler of the year in 2010.

The following summer, the sport had to take a back seat after Betts was drafted in the fifth round by the Boston Red Sox.

The former American League most valuable player never abandoned it, though. Instead, Betts adopted bowling as his primary offseason activity, estimating he frequents the lanes as often as six days a week during the winter, typically bowling six to eight games each time.

Asked whether any of his bowling skills translate to baseball, or vice versa, Betts was quick to answer.

“They’re two completely different things,” he said. “Two different mindsets.”

After nine years in the big leagues, though, that’s kind of the point.

Betts has never solely been a baseball junkie. In high school, he was also a serious basketball player. In adulthood, his varied interests have continued, from online gaming to involvement in media projects such as a Jackie Robinson documentary he helped produce for Fox Sports last year.

His offseason bowling routine helps him find a balance between it all — providing a reprieve from the grind of a nine-month major league season and a stimulant for a different set of mental and physical skills.

“I use one,” Betts said of bowling and baseball, “to get away from the other.”

Before long, Betts’ focus will shift back to the diamond.

On Wednesday night, though, he was still squeezing one last bowling tournament out of the offseason, hosting a charity event at L.A. Live, decked out in a black-and-white, retro-themed “MB”-emblazoned uniform, with a satisfied grin on his face.

“It’s just a passion that I have,” he said. “I’m always gonna keep it.”