When Alex Rodriguez made his major league debut with the Seattle Mariners in 1994 at age 18, he was the youngest player in the league.  Strangely enough, turning 40 years old last week, he is among the oldest players in the sport.  He’s now the “Ancient Mariner” of baseball because the sport is being dominated by younger players.  Twenty of the players in the All-Star Game a couple of weeks ago were age 25 and under, the most in history.  These guys were five years old or less when A-Rod broke into the big leagues.

I recently saw a stat on the website mlb.com that 11 of the 30 major league teams had a player 25 and under leading them in Wins Above Replacement, a metric for evaluating comparative performances of players.  That tells me that youth is not watering down the quality of the players coming into the game.

The average age of all the teams in Major League Baseball in 2015 is 28.6 years.  The Yankees and Reds are the only teams with an average age of 30 and over this year.  Ten years ago, there were ten teams in this category, and there were no teams with an average age under 27.2 year.  This year the Astros’ average age is 26.3, with the Diamondbacks (26.8) and Cubs (26.9) not far behind.  Yet the relatively younger age of these teams hasn’t been a detriment in their competitiveness, since the Astros and Cubs are in the mix for playoff spots.  For a sport that has historically embraced the use of older players (e g., Jamie Moyer pitched until age 49 in 2012), that may now be changing.

The youth movement didn’t just happen this year.  It’s been in the making for a while.  However the emergence of many young stars who are now excelling in the game has brought new attention to the situation.

Here’s a sampling of some of the top players 25 years old and under.  Despite their youth, they have already been dominating the game.

Mike Trout has one American League MVP title to his name, being a runner-up twice.  He’s been MVP of the All-Star Game twice.  He has already been compared to some of the greats of the games.

Madison Bumgardner has already won three World Series championships.  He was the MVP last year in one of the most memorable Series performances in history.

Bryce Harper, the National League Rookie of the Year at age 19, has been an All-Star twice and in the race for the MVP Award this year.

Giancarlo Stanton already has 181 career home runs, while being selected to three All-Star Games.

Jose Fernandez was third in the National League Cy Young Award voting in this rookie season at age 20.

Jose Altuve is a three-time All-Star who led the American League in hits and stolen bases last year.

Freddie Freeman is already in his sixth major league season, including two All-Star appearances.  He’s been averaging over 90 RBI per season.

Jason Heyward is also in his sixth major league season and is generally regarded as the best defensive right-fielder in the game.

Many Machado has emerged as one of the best-fielding third baseman, and he can hit for power, too.

Michael Wacha debuted the majors just one year out of college, hurling three wins for the Cardinals in the 2013 post-season.  He’s having an All-Star season this year, after suffering arm injuries in 2014.

Sonny Gray has already recorded 30 wins since July 2013, essentially the equivalent of only two full seasons.

Newcomers in 2015 include youngsters Kris Bryant, Joc Pederson, Carlos Correa, Noah Syndergaard, and Mookie Betts.  They are already making positive imprints on the game with their performances.

The youth movement is definitely a good thing for baseball.  It comes at a time when the sport recognizes it must attract a younger base of regular followers and fans to remain popular.  The increasing number of younger players on the field is generating excitement and naturally helping the sport’s marketing pitch.  The fact that younger players are generally more accessible via social media and are more visible in media advertisements also enhances their potential appeal to younger fans.  A business indicator of the growing popularity of these younger players is that they rank among the top sellers in uniform jerseys.

This emergence of today’s young stars has been compared to baseball’s era of the early-to-mid 1950s when there was a dominance by young upstarts named Mays, Mantle, Aaron, Mathews, Robinson, Banks, Kaline, and Ford.  That’s some pretty darn good company. Perhaps we are seeing the development of a new Golden Age of the game.