This piece looks at how differences in biological development can slip through the cracks of player assessment in academies, drawing on research findings, systemic causes, and possible solutions.
Picture a 13-year-old slicing through two defenders and scoring. The whole stand is chanting that they’ve found the next Ronaldo.
Now picture another boy the same age, sitting on the bench: smaller, clumsier with the ball at his feet. Nobody even knows his name.
From what I’ve seen during my time in academies, and from the research on the subject, the gap between these two boys isn’t always about talent. More often than not, the deciding factor is the difference in how their bodies are developing.
Sports science has a name for this: maturation bias, mistaking the temporary physical edge that comes with early biological development for genuine footballing talent.
Sports science has a name for this: maturation bias, mistaking the temporary physical edge that comes with early biological development for genuine footballing talent.
Let’s look at how this invisible bias has opened up a genuine crack in youth football systems, backed by clear findings from the research.
What’s Actually Happening in Academies?
- The Relative Age Advantage: A ten-year study followed 198 players from the academies of two Spanish professional clubs [1]. The finding was clear: the large majority were born in the first half of the year. In other words, selection into the academy is already being shaped less by footballing ability than by the temporary size advantage that comes with being born earlier in the year.
- The Unconscious Height Illusion: An AI-based study in England exposed coaches’ biggest blind spot [2]. The strongest predictor of the development scores coaches gave players wasn’t passing quality or game intelligence; it was how physically mature the child was and how close they were to their adult height.
- The Confession on the Field: A study carried out at a Premier League academy in England documents the admission itself [3]. Coaches believe they focus on technique and tactics, yet they openly admit that when selecting their starting lineup, they consciously favor the biggest, earliest-developing children, because winning through physical power is simply the easier route in the moment.
So Why Does the System Fall Into This Blind Spot?
- Pressure to Win: Coaches openly admit that in cup matches or high-stakes moments, they’ll sideline late developers and start early developers just to get through the day, because results on the table have a direct bearing on a coach’s job security and reputation.
- The “Fixed Label” Trap: Once a child is tagged early on as “Group A” or “high potential,” later coaches struggle to question that label even when performance drops off. Investment in early developers continues uninterrupted, while late developers slip through the cracks [4].
- Adolescent Awkwardness: During the growth spurt around age 14-15, bones and muscles grow at uneven rates, and coordination temporarily suffers. The kid who was threading passes through the eye of a needle yesterday suddenly looks clumsy. That temporary dip in performance can be read as a permanent lack of talent, pushing players out of the system too early.
That temporary dip in performance can be read as a permanent lack of talent, pushing players out of the system too early.
So What’s the Solution?
Complaining about it isn’t enough. Clubs need to take real, structural steps:
- Bio-Banding: Group and play children not just by the birth year on their ID, but by their bone, muscle, and overall biological development. This prevents children being physically overpowered and losing confidence.
- Fairness in Both Directions: This system doesn’t just protect late-developing, physically slighter children. It does early developers a favor too. Moving a child who breezes through their own age group on physical strength alone up to an older group, where they’ll face genuine physical resistance, teaches them to compete early, and that’s exactly what will serve them best once the physical gap closes later on.
- Explaining the Process to Families: Without a clear explanation, this can come across as punishment or a step backward, leaving the child feeling inadequate. Keeping parents informed and providing psychological support is critical here.
- Shadow Squads: As the Belgian federation and several Premier League clubs already do, parallel teams should be set up for technically gifted but late-developing children, and final cut decisions should be pushed back to age 16-17.
- Regional Monitoring Networks: Instead of abandoning players who leave the academy to their fate, we should route them to regional teams, keep tracking their progress, and remove the barriers that stop them re-entering the system once their physical development catches up.
- Managing Training Load: Don’t cut a child just because a growth spurt has made them clumsy. Give them room to breathe; this phase lasts a season or two at most. Managing this developmental window properly matters both for performance and for player health.
Conclusion
We have to stop academies from being sorting centers for early-developing big kids and turn them into genuine talent factories. None of this is simple, of course; it takes resources and institutional patience. But if we don’t act now, the talent we lose won’t come back tomorrow.
The slight kid we’ve forgotten on the bench today could be the team captain in three years’ time. All he needs is for us to give him those three years.
The slight kid we’ve forgotten on the bench today could be the team captain in three years’ time. All he needs is for us to give him those three years.
Sources
[1] Moran, J. et al. (2024). “The Identification and Development of Young Talent in Spanish Soccer Academies: A 10-Year Multi-Study Follow-Up”, International Journal of Sports Science & Coaching, 2024
[2] Kelly, A. L. et al. (2022). “A Multidisciplinary Investigation into the Talent Development Processes at an English Football Academy: A Machine Learning Approach”, Sports (MDPI), 2022
[3], [4] Hill, M. et al. (2025). “Adolescent Player Development within Institutional Constraints in Academy Football”, International Journal of Sports Science & Coaching, 2025