To understand what is happening in Major League Baseball, let's begin with the All-Star Game.

Of the eight 21-or-under players who have appeared in a big league game this season, four are All-Stars, according to research by Sports Illustrated, which also reported that no other All-Star Game in history had that many players that young.

Two of the four -- Bryce Harper and Mike Trout -- will be playing in their second All-Star Game already, while the other two -- Manny Machado and Jose Fernandez -- will be in their first.


Wait, there's more.

Seven players 23 or younger were named to this year's Midsummer Classic, and another five are under 26. And check out the names. Giants left-hander Madison Bumgarner, all of 23, made his debut at 20 and has already pitched in two World Series.

D-backs left-hander Patrick Corbin is also 23, and he might be baseball's best pitcher in 2013. Chris Sale and Matt Harvey, aces of the White Sox and Mets, respectively, are 24. Jean Segura, Milwaukee's slick-fielding shortstop, is 23.

Welcome to baseball's next generation of talent. Players are being promoted more quickly than ever, and they're showing that they belong.

Their impact has been felt in every front office in the game. Rather than trade for proven stars or throw millions at free agents, teams are taking another look at their own guys.

Seven players from the 2010 First-Year Player Draft have spent time in the Major Leagues, and four of them -- Machado, Harper, Sale and Harvey -- are 2013 All-Stars. Four players taken in the 2012 Draft have logged time in the big leagues.

Once upon a time, baseball people believed that young players had to be handled cautiously. If they were rushed, their development might be damaged, their careers perhaps ruined. At least that was the thinking.

Never mind that Willie Mays, Cal Ripken, Frank Robinson, Carl Crawford and a host of others were all of 20 when they made their Major League debuts. Ken Griffey Jr. and Mickey Mantle were 19.

Perhaps those six are a poor example, because all were extraordinarily talented. But in recent years, as teams worked hard to keep their best players from reaching the free-agent market, clubs searching for talent were forced to adjust their thinking.

From the moment the Nationals made Harper the first pick of the 2010 Draft, team officials began getting questions about his schedule for reaching the Major Leagues. Rather than answer the questions, they allowed Harper to set his own timetable.

Harper flew through the system, playing 109 games that first season. He finished the year in Double-A and played 21 games in Triple-A the next season before joining the Nationals.

He has had some slumps and injuries, but there never has been a time when he seemed awed or overmatched.

Machado was the third overall pick of that same Draft; the Orioles had him play 219 games in the Minors. Baltimore debated how quickly to bring him up, finally deciding to skip Triple-A and stick him in the big league lineup on Aug. 9.

The Orioles were 33-18 with him in the starting lineup, and as with Harper, Machado was never overwhelmed by either the competition or the circumstances. Now, at 21, he's hitting .315 and arguably one of the best players in the game.

Harper's success may have played a role in the rapid promotion of the Nationals' No. 1 pick in 2011, Anthony Rendon. Rendon batted .240 in eight games in April and May, then was returned to the Minors for a month. He's hitting .308 since and has helped propel the Nationals back in the National League East race.

The point is that the Nationals could not have traded for someone as talented as Rendon. And if a player with anything approaching his gifts had been available, it would have taken a bounty of prospects to get him.

All of these success stories -- Harper and Trout, Machado and Rendon -- surely played a role in the Dodgers' decision to promote Yasiel Puig, 22, to the big leagues after a mere 63 games.

The Dodgers knew there were things Puig still had to learn about the game, but they also believed he has the kind of physical gifts that don't come along that often. They also believed that the team would feed off his energy and enthusiasm.

Puig began Tuesday hitting .409, and the Dodgers are 20-12 with him in the starting lineup. They've closed their deficit in the NL West from 9 1/2 games to 3 1/2 games in the last two weeks.

Puig makes plenty of mistakes. He crashes into walls. He runs the bases recklessly. He also is playing so well and with so much enthusiasm that it has affected everyone in their clubhouse.

Like Harper and Trout, like Machado and the others, Puig has prompted every baseball man to take a second and third look at his own system. Maybe the old rules don't apply anymore.

These kids are part of what make this All-Star Game special. It's for such established stars as Joey Votto and Miguel Cabrera, but it's a chance to show off a new generation of talent and a new way of evaluating talent.