Selection of the oldest: relative age effects in the UEFA Youth League

Differences in age within annual cohorts (relative age) result in performance discrepancies between children and youths and also bias the talent selection process in many sports. The consequences stemming from the relative age approach are referred to as relative age effects (RAEs). In this study, we analysed the prevalence of RAEs according to the playing positions and countries of 1208 youth soccer players who participated in the new UEFA Youth League. Our comparisons showed significant RAEs with medium effects. Youth players born in Q1 were 3.35 times more likely to be selected than players born in Q4. Significant RAEs were found for every age group (1996, 1997, 1998 and 1999), but younger age groups showed significantly higher RAEs than the older age groups. The analysis did not reveal any influence of playing position on the size of the RAEs. However, the results showed significant differences in relation to country, as well as the absence of RAEs in players from Belgium, Bulgaria, Cyprus and Slovenia. All in all, the UEFA Youth League is highly biased by RAEs. Thus, it seems RAEs reflect a type of developmental barrier that is preventable if appropriate solutions are implemented in the future.