The Boston Red Sox never know what Kristian Campbell will do next. He might dive to his left or spin to his right at second base to make a play that makes his teammates gasp, as he did so often this spring that he forced his way onto the major league roster. He might become the 14th player in the last 50 years to reach base safely in his first 17 career games, as he did Monday with a solo home run. Or he might say something that leaves the clubhouse reeling, as he does just about every day.

The Red Sox first learned how wide-eyed the 22-year-old Campbell was before the season started, when the team traveled to Monterrey, Mexico, for an exhibition series against the Monterrey Sultanes. As the Red Sox checked into their hotel, Campbell asked, “Who’s my roommate?” Manager Alex Cora gently explained that you get your own hotel room in the big leagues.

Campbell was similarly shocked a few days later to learn that the team has its own airplane. Once he got to Boston, he cracked them up by referring to his fellow Red Sox not as his teammates but as his friends. He introduces himself to fans, as if they are not already wearing his jersey.

Campbell is a key member of a Red Sox team that has a real chance to win the American League East for the first time in seven years. He is the new beneficiary of an eight-year, $60 million contact extension. And at the moment, he is Boston’s Greenest Monster.

“Honestly, I’m happy, because he’s just where his feet are at,” says 28-year-old left fielder Jarren Duran. “He’s not looking ahead.”

The stories now verge on the apocryphal: Teammates—friends—say he grew up idolizing Padres right fielder Fernando Tatís Jr. (age 26), that he has never heard of Baltimore Orioles righty Charlie Morton (pitching in his 18th season, five of those for Campbell’s hometown Atlanta team), that he’s pretty sure the famous basketball player who sticks his tongue out is LeBron James.

Campbell acknowledges most of it is true, although he takes issue with that last one. “I know who Michael Jordan is,” he insists. (And for the record, whether he was familiar with Morton’s oeuvre or not, Campbell worked a 3–2 count in their first meeting last week, then hit a two-run homer.)

Campbell does not mind being cast as the innocent rookie. “I’m still a senior in college,” he says. “I got drafted out of my sophomore year, so last year was my junior year. This [would be] my senior year if I was still in school. You’ve gotta put it in perspective.”

Perhaps Campbell’s greatest tool is his ability to do just that. Before his first game, in Arlington, Texas, he found himself gazing at the crowd. He might have made eye contact with each of the 37,587 fans in attendance. There’s a lot of people here, he thought. But he took a breath and reminded himself that he was playing the same game he loved as a dirt-covered Little Leaguer in Chattanooga, Tenn.; a 2023 fourth-round draft pick coming out of Georgia Tech; and last year’s Baseball America Minor League Player of the Year. By his second or third major league game, he says, he was able to limit his vision to the first deck of fans. And now, as a veteran of nearly three weeks? “I’m locked in,” he says. “Back to normal type of locked in.”

Campbell has played mostly second base this season but has also gotten starts in center field and left field. / Eric Canha-Imagn Images

He rates that first game as his favorite day of his young major league career, because the team won. He is reminded that six days later, he signed that eight-figure deal. “That’s outside of baseball,” he scoffs. “I mean, that’s about baseball, but it’s not baseball.” He heard the people who questioned whether a player of his talent had settled for too low a number. “It’s life-changing for me and my family,” he says. “That’s all that matters. Two years ago I was in college and had nothing.”

He adds, “I got a great opportunity with the Red Sox, to play with this team, with this organization, and to help this team win. And everybody doesn’t have that opportunity. So I think of it that way, and try to take advantage of the opportunity as much as I can. And don’t be too greedy when it comes to the contracts and stuff—you know, take what you’re given and be grateful with that.”

That gratitude shows up nearly everywhere. He has commented on the big league food, big league hotels, even big league stadium roofs. “He’s just the sweetest kid,” says outfielder Rob Refsnyder. “He’s so innocent. We all love him, man. He works hard. He’s kind of goofy, shameless. It’s good.”

For three hours every day, though, that gratitude disappears. “I like the fact that he’s been here for a week and he expects to be perfect and great every single at-bat,” says first baseman Triston Casas. “He doesn’t want to give himself a learning curve. He doesn’t want to accept the fact that he’s a rookie or that he’s the youngest guy. He feels like he’s entitled to as much success as anybody else, which I love about him. And he feels like he should get a hit against every single guy, like no situation is too big and that he should make every single play.”

Campbell is slashing .328/.420/.552 with three home runs in 17 games. / Eric Canha-Imagn Images

These were the traits the Red Sox seized upon when they signed him for $492,700 after his redshirt sophomore year at Georgia Tech. He’d always had good bat-to-ball skills, but scouts were so unimpressed with his power potential that he went undrafted coming out of high school. The Boston player development staff worked with him to lift his bat path and add some 20 pounds of muscle. Campbell spent his entire 2023–24 offseason at the team’s complex in Fort Myers, Fla., working with the hitting coaches. He proceeded to rocket from High A to Double A to Triple A in one season, hitting .330 and slugging .558. (When other prospects saw his results, The Boston Globe reported, they signed up to do the same this past winter; the team had to cap enrollment at 50 or so.)

“I think it’s just this unwillingness to ever kind of accept that he can’t get better, he can’t make an adjustment,” says chief baseball officer Craig Breslow. “There’s a balance between humility and confidence, and you don’t want either to supersede the other. And he has the right balance. From the time that he was drafted, before I got here, the [player development] group raved about his curiosity, his interest in learning what others believe could make him better, but he also had a really good grasp of his own identity, what his strengths were, what he what he wanted to preserve and maintain as as he evolved.”

That combination of humility and confidence reminds Cora of another skinny former Red Sox prospect: Mookie Betts. Cora used to joke that his only job as manager was to remind Betts, who set for himself a standard that he almost never reached, that he was good at baseball. He sees those instincts in Campbell. “At one point, he’s gonna go through something,” Cora says. “0-for-10 with five strikeouts or 2-for-20, and we’ll remind him he’s a good player. He’s very hard on himself.”

So far even Campbell has had a hard time spotting flaws in his game. There have been so many highlights already—a ninth-inning Opening Day single that set up the winning run, a two-double game, that home run against the Orioles—but hitting coach Pete Fatse points to a quieter one, in a game the Red Sox lost.

Blue Jays righty Kevin Gausman had struck Campbell out looking twice, and the Red Sox had mustered only three baserunners. Fatse reminded the hitters not to lose focus, that eventually Gausman would make a mistake. “He was ready Pitch One, and he hit a hard groundball [single] up the middle,” Fatse says. “And that’s not the sexy answer, but those are the moments that get you through when you don’t feel 100%. When you see a guy able to work through a situation like that, it just continues to breed confidence.”

The Red Sox lost that game, but Campbell showed up the next day beaming. He was having so much fun.