Nationals outfielder Bryce Harper will play in his second All-Star game on Tuesday.

The Golden Age of Baseball came to an end about 50 years ago. Since then, the league has gone through expansion, endured a strike and dealt with a major steroid problem. Baseball has changed, but the recent influx of talented young ball players could mean another golden age is upon us. Three position players 21 or younger — the Nationals’ Bryce Harper, the Angels’ Mike Trout and the Orioles’ Manny Machado — will play in Tuesday’s All-Star game (8 p.m., Fox). This crop of phenoms resembles some of the greatest players from the Golden Age.

Mike Trout

Golden Age comparison: Willie Mays

Why they’re alike: Mays is the best five-tool player of all time. Trout, meanwhile, had one of the best all-around seasons in baseball history last year. In 2012, the Angels outfielder batted .326 with 30 home runs, 83 RBIs, 129 runs and 49 stolen bases in 139 games, finishing second in the AL MVP voting. Mays became one of the youngest MVPs when he won as a 23-year-old in 1954. The Giants center fielder led the league in batting, slugging, OPS and triples that year.

Making history: Last year Trout, 21, became the youngest player to hit 30 home runs and steal 30 bases in a single season. He needs 15 homers and nine steals in the second half to reach that feat in back-to-back years, something Mays did in 1956-57.

Surprising stat: Batting average in first 271 games of career

Trout: .312      Mays: .293

Bryce Harper

Golden Age comparison: Mickey Mantle

Why they’re alike: Before Harper even reached the big leagues he was compared to Mantle, who was a baseball prodigy himself. Both made their major league debuts as teenagers. Harper’s hard-nosed style of play, athleticism and raw power resemble Mantle’s. In his career, the Yankees outfielder averaged a home run every 15.1 at-bats. This season, Harper has averaged one homer every 15.5 at-bats. Mantle lived up to his enormous hype as a teenage phenom. Harper, who at 20 will be playing in his second All-Star game Tuesday, seems on his way to doing the same.

Making history: Last year, Harper was the youngest position player to play in an All-Star game. The outfielder went 0-for-1 with a walk and a strikeout. This year he’ll be the youngest player ever to start for the NL.

Surprising stat: Home runs hit before turning 20

Harper: 22    Mantle: 13

Manny Machado

Golden Age comparison: Brooks Robinson

Why they’re alike: Anyone who plays third for the Orioles will be compared to Robinson, who was the best defensive third baseman in baseball history. The Hall of Famer won 16 Gold Gloves. He also was the 1964 AL MVP, 1970 World Series MVP and an 18-time All-Star. Machado is on his way to his first Gold Glove. On top of making spectacular plays on a regular basis, he’s consistent. Among third basemen, Machado’s second in the AL in fielding percentage (.980) and leads the majors in double plays made. His Defensive WAR (2.7) is 1.0 better than anyone else at his position.

Making history: Machado is on pace to hit 66 doubles, which would be one shy of the single-season major league record. His 39 doubles is already more than Robinson ever hit in one season.

Surprising stat: Errors in first 147 games of career

Machado: 11    Robinson: 16