Earlier this month, in Cincinnati, Bryce Harper joined several teammates strolling from the stadium to the team hotel. The group included Ryan Zimmerman, Xavier Nady and Adam LaRoche, all of them in a different stage of life from Harper.

On the field, where he has quickly become a star, the Washington Nationals disregard his age. On this walk home, where his 19 years made him something like a little brother, playful conversation turned toward the topic.

“We figured it out that Bryce was 8 when Adam got married,” Zimmerman recalled Wednesday, breaking into a wide smile.

Harper’s first month in the major leagues will have elapsed by the end of this weekend, after the Nationals’ three-game National League East showdown against the Atlanta Braves. The Nationals planned for him still to be in Class AAA Syracuse at this point. He has instead provided a crucial boost to an injury-ravaged, first-place team. And he has done so while learning about life in the majors at 19.

“I don’t think anybody looks at age,” Harper said. “They look at maturity and whatnot. They’ve helped me out in that aspect also. I’m just trying to be another guy in the clubhouse and not the kid who comes in and thinks he’s great. I try to come here like every other guy in this clubhouse, and try to have fun.”

Harper has not eased into the majors. He has started all 24 Nationals games and played in all 221 innings since he arrived. He has started at all three outfield positions — 13 games in right, six in left and five in center. He has batted seventh, third, fifth and second. When the Nationals have needed almost anything, they have asked Harper.

“I didn’t expect him here as quick as he’s here,” Manager Davey Johnson said. “I didn’t expect him to look as comfortable as he looks up here. I think he’s very relaxed and I think he’s having fun, and I think he’s expressing his talent. It’s much needed.”

Harper’s performance, for his age, has bordered on historic. Among 19-year-olds with at least 100 plate appearances since 1900, only Mel Ott (.921 in 1928), Jimmie Foxx (.908 in 1927) and Tony Conigliaro (.883 in 1964) had a higher OPS (on-base percentage plus slugging percentage) than Harper’s current .816.

Here, then, is a partial list of players whose OPS, in their age-19 season, was lower than Harper’s mark: Ty Cobb, Ken Griffey Jr., Mickey Mantle, Freddie Lindstrom, Robin Yount, Alex Rodriguez and Al Kaline.

“I’m not surprised,” Zimmerman said. “As talented as he is and mature as he is, baseball-wise, I didn’t really think he was going to have any problem hitting.”

Nothing has fazed Harper, not even life among grown men as a teenager. Harper’s two youngest teammates, Stephen Strasburg and Steve Lombardozzi, are four years older than him, and Strasburg has been married for more than two years. In most any workplace, one 19-year-old among 24 fully formed adults would create a unique, perhaps awkward, dynamic. Baseball, with its naked emphasis on performance, is different.

“With your co-workers, you don’t ever say, ‘Hey, how old are you?’ ” shortstop Ian Desmond said. “If you’re in the big leagues, you’re in the big leagues. You’re either good or you’re not good. If you’re out there doing your job, having success, age is totally irrelevant. Success kind of breeds respect.”

Said Johnson: “The only way I know he’s young is when I look over at some of the girls. They call themselves ‘Harper’s Hotties’ or something. They look like they’re about 16.”

Teammates have uniformly praised Harper’s demeanor. Desmond credited the Nationals’ minor league staff for teaching him how to play with focus and hustle. Harper may not have the breadth of experience his teammates do, but he took one of the same rites of passage they did: He rode buses in the minors for a full year.

“From a maturity perspective, from the first spring training to this spring training, it was night and day,” Zimmerman said. “I think him playing in the minor leagues and getting a full year of professional baseball, being away from home and kind of out of his comfort zone, I think that helped him a lot.”

Wednesday, Harper yanked bulky headphones over his ears and fiddled with an iPad for more than an hour. He chatted briefly with starting pitcher Edwin Jackson, then went back to minding his own business.

Harper’s unique background has helped the experience of playing in the majors as a teenager feel almost normal. Growing up, Harper crisscrossed the country and joined new AAU or all-star teams almost every weekend. His ability earned him invitations to play in youth tournaments with older players. If he was 14, they were 15 or 16. He learned the social art of blending in.

“I was always the new guy on the team,” Harper said. “I’m not trying to go in there and go, ‘Hey, I own this team.’ I don’t have to be that guy who puts everybody on my back.”

Harper mentioned Zimmerman, LaRoche and Rick Ankiel as veterans he has leaned on. He has missed Jayson Werth’s influence on the road since Werth broke his wrist.

“J-Dub, you know, he helped me every day with outfield and base-running, how to face pitchers,” Harper said. “Having him around was the biggest. Him getting hurt, that [stunk]. That was my guy. That kind of put me down in the dumps a little bit. But I’ve got everybody else.”

His comfort has allowed Harper to focus on baseball, and he has made one crucial tweak. In his first 42 plate appearances, Harper drew six walks and struck out four times. As he moved up in the batting order, pitchers fed him more off-speed pitches out of the zone, and he whiffed 12 times and walked three times in his next 43 plate appearances. He has recently started to find his original patience, striking out twice and walking twice since.

“When he first got up here, he was really calm and slow, taking some walks,” hitting coach Rick Eckstein said. “And then he started going after pitches that were off the plate, started getting a little antsy with the bat. He was striking out a little bit and he should have been walking instead. He made that adjustment.”

The Nationals remained open to sending Harper back to the minors when they first promoted him April 28, but his play has made clear he is where he belongs. Asked the best about the majors, Harper responded, “Everything.” He has been one of the Nationals’ best players, a 19-year-old they would not be whole without.

“He’s been great,” Desmond said. “I can’t wait to see what’s to come.”