Mike Trout and Bryce Harper pictured together at the 2012 All Star Game (Photo: SI).

The All Star Game is usually a showcase for baseball’s most established veteran superstars, but even with the presence of iconic players like Derek Jeter, Justin Verlander, and David Ortiz, most of the focus during this year’s Midseason Classic seemed to be on the game’s two youngest players. Beyond celebrating the obvious talents of the Angels’ Mike Trout and Nationals’ Bryce Harper, however, was the sentiment that the two phenoms represented a youthful resurgence brought about by steroid withdrawal. Although that line of reasoning fits nicely into the anti-steroid narrative,  is baseball really undergoing a transition to younger players?

Distribution of Major League Debut Ages, by Decade

Note: Total includes all players who debuted at the age of 21 or younger. Team Seasons is the sum of all teams in each year.
Source: Baseball-reference.com

Because Harper and Trout are so immensely talented, it is easy to see why their presence would overshadow the underlying trend. Since the 1970s, position players have been promoted at an increasingly older age, while younger pitchers have debuted at a steady rate. Even the most recent data falls in line with these trends. It might seem like Trout and Harper are leading the march of youth, but aside from the Nationals’ rookie, only five (four pitchers and one hitter) other players below the age of 22 have made their major league debut in 2012.

Distribution of Call-Ups, by Month

Note: Includes all players who debuted at the age of 21 or younger.
Source: Baseball-reference.com

With over one half the season remaining, it’s possible that 2012 could wind up yielding a bumper crop of young talent, but it’s worth noting that over the last 20 years, the number of prospects promoted in the second half, and particularly in September, has declined significantly. Instead of the traditional practice of giving young players a chance to experience the majors at the end of each season, teams are now allowing the arbitration clock to determine promotions. As a result, players with the potential to impact the pennant race are being called up in the middle of the season (usually in mid-June to July, when they can’t accrue enough service time to shave a year off team control), or not at all.

Average Major League Baseball Player Ages

Note: Graph is not a time series, but rather an average age sampling from the start of each decade compared to 2012.
Source: Baseball-reference.com

Even though the number of active 40-somethings has been on the decline, baseball is still an “older” man’s game when compared to the past. The arrivals of Harper and Trout have certainly been exciting developments, but what makes each player so special is more their talent than their tender age. Granted, the combination of Trout’s and Harper’s youth and ability make them a particularly dynamic duo, but baseball fans shouldn’t expect too many similar cases to emerge in the near future.