At every turn, school sports are effectively rigged for children born soon after the school start cutoff date — which varies by state in the U.S. but is
most commonly around Sept. 1 — and against later-born children. Yet in the NBA, James Harden
1 and Kobe Bryant
2 are among the former MVPs born in August, putting them among the youngest in their school year group. In baseball,
Mike Trout and
Cody Bellinger were each just 17 years old when they were drafted;
Tom Brady and
Barry Sanders are among the NFL MVPs who were young for their cohorts.
These athletes embody a notable paradox: Once they reach professional levels, younger-born players tend to be more successful and are overrepresented among “super-elite” athletes.This phenomenon, found across a range of sports and explored in “
The Best: How Elite Athletes Are Made,” a book I co-authored, is known as the underdog effect. Essentially, it is harder for later-born children to become professional athletes — but if they do become professional, they have a higher chance of becoming among the very best players in their sport.
A study of the most valuable male players in professional soccer, ice hockey, baseball and Australian rules football
analyzed their birth dates relative to the selection year for the sport in their country. The finding was the opposite of the relative age effect: Players born later for their year were overrepresented among the very elite, accounting for a combined 55 percent of players.
“Award-winning athletes were more likely to be born late in the selection year than early in the year,” wrote Paul Ford and Mark Williams, the authors of the study. “The relatively younger athletes in our sample were able to stay in a developmental system that discriminated against them.” The authors suggested that “to survive in the system, relatively younger athletes must develop some other performance advantage, which is likely to be skill and its attributes, such as speed, technique and decision making. During their development, these younger athletes may benefit further in skill acquisition by playing the sport with relatively older athletes.”
In other words, the very same factor that worked against athletes young for their selection year became an advantage if they could hold on in the system. Among super-elite athletes, the relative age effect not only fades but reverses.
The difficulties faced by later-born children on the sports field can help them develop in advantageous ways. A study of
Premier League soccer academies found that players who were later maturing for their year — sometimes because they are young for their selection group, but also because they are physically late maturers — are more adept at self-analyzing their games and improving their weaknesses.
German youth soccer players born in the last quarter of the selection year were found to perform worse than others in their age group — but, when taking relative age into account, the players born in the last quarter were, on average, better performers. “The superior abilities of late-maturing or quarter-four players is due to the greater challenges experienced and superior skills that are required to overcome these,” said Sean Cumming, a co-author of the Premier League paper.
Failing to recognize the talents of later-born children can be costly. At the age of 8, a young Harry Kane was released from the academy of the soccer team he supported, Arsenal. “He was a bit chubby, he wasn’t very athletic,” Liam Brady, Arsenal’s former academy director,
told The Telegraph in 2018. Kane was both young for his school year — born on July 28, one month before the end of the English school year — and was also a late developer biologically for his age. After being released by Arsenal, Kane was signed by the academy of Tottenham Hotspur. He has now scored
more than 200 goals for Tottenham and is valued at
well over $100 million.