Selection, Not Adaptation: Why Transfer Age Predicts Who Clubs Buy and Not How They Play

Playing time is the product of two coaching decisions, whether to field a player and how long to leave him on, and transfer age should bear on them differently. Using 3,849 permanent transfers into Big Five clubs between 2010 and 2024, with playing time from match records, we reproduce the familiar inverted-U in transfer age, peaking at 28.4 years. It disappears once the player’s market valuation enters. So does its counterpart across 30,260 player-seasons in the five leagues, where the peak is sharper at 28.5 years and the quadratic term turns positive under the same control. The mechanism is visible directly. Clubs buy players who have been playing, and against matched non-movers a signing loses no playing time on arrival. What survives conditioning is concavity in minutes per appearance, and only among forwards. Transfer age tells us which players are bought at what price, not what becomes of them afterwards.