With his team pushing for an equalizer in the final seconds of a match against Arsenal last month, Swansea midfielder Leroy Fer found himself in a footrace with Alex Oxlade-Chamberlain, one of the Premier League's fastest players. Knowing he would lose on speed, Fer tried to get his body between Oxlade-Chamberlain and the ball, and this is where things got interesting. Fer is three inches taller and looks a good deal heavier than Oxlade-Chamberlain, yet the Arsenal attacker shrugged off his larger opponent as though he were a winter jacket. When, seconds later, Oxlade-Chamberlain crossed the ball to the feet of Theo Walcott, Fer was still lying on the grass. Swansea would lose, 3-2.
As the replays rolled, the announcer praised not just the quickness but also the power of Oxlade-Chamberlain. Years ago, when he was in the youth academy at Southampton, such a compliment might have been hard to imagine. Oxlade-Chamberlain was small for his age, a late bloomer.
"He hit a point in time where he was not close to getting released, but there was a decision whether he was too small to play within his age group," says James Bunce, the Head of Sport Science in the Premier League and the former Head of Athletic Development at Southampton. The Southampton coaches weren't sure what to do with Oxlade-Chamberlain. "We came to the decision that instead of moving him up in age group, we'd keep hold of him and play him down a year."
In the U.S., the practice of having grade schoolers repeat a year for the athletic edge is often called "reclassifying," and it occurs primarily among promising football and basketball recruits; it isn't something you typically hear about in soccer academies. Rather, it's the opposite: gifted players often "play up," training with older players rather than their own age group. The theory is that by playing up, a young, bright talent will develop more quickly thanks to the added challenge of dealing with larger, more technically advanced opponents. But hold a player back a year—and not just any player, but one of England's brightest young talents? This was unorthodox.
Yet the decision paid dividends. According to Bunce, Oxlade-Chamberlain's confidence's was one of the main beneficiaries. Because he was now training with players closer to his own size, he was able to use his ability without worrying about "getting smashed off the ball," as Bunce remembers it. When Oxlade-Chamberlain finally started growing into the five-foot-eleven frame he now inhabits, he wasn't behind his age group; he was ahead. Oxlade-Chamberlain made his Southampton debut when he was just 16.
This got Bunce and his Southampton colleagues thinking. By ignoring Oxlade-Chamberlain's age and instead focusing on getting him a suitable physical matchup, they put him in an environment that helped him succeed. Maybe other players would excel in similar scenarios. Maybe it was time to rethink the role age plays in youth development altogether.
In soccer academies the world over, chronological age determines a player's peer group, and judgments on that player's ability and potential are made largely through comparisons within that group. But the system has a flaw: within those age groups, physical maturity can vary wildly.
About a decade ago, researchers began noticing a phenomenon that would later become known as the Relative Age Effect, which holds that players born earlier in a calendar year are more likely to excel athletically than those born later in the year. In England, the cut-off date for a yearly cohort is September 1st, which corresponds with the beginning of the school year. Last year, the BBC cited figures showing players born between September and November—the first quarter of the year—account for "45% of the intake" in Premier League academies, "whereas those born in the June-to-August quarter provide just 10% of the young players."
This makes some sense: kids who are a few extra months older have had a few more months to grow, and it's easy to mistake size with skill at this stage. But it turns out the interplay between physical maturity and age is far more complicated than the RAE suggests, especially when kids enter puberty.
Between the ages of 12 and 16, there exists "massive, massive variance in where the boys are, physically and maturationally," says Chris Hedges, a physiotherapist at Norwich City FC. "You watch some games and the best player is the early developer, who has more lean skeletal muscle mass, who has a better developed nervous system, who can generate power quicker or change in direction. And, of course, if he's much bigger than his counterpart, he runs past him. He holds him off. He looks really good in that snapshot, where he is in that space and time."
Even if that advantage would be only temporary, disappearing once the late developers catch up, it leaves an impression on coaches. At this stage, smaller players are often cut from academies; according to a study by the program's expert advisory group, late-developing boys born in the last quarter of their year are 20 times less likely to sign a contract.
This doesn't mean they can't find success, but it certainly complicates things. Jamie Vardy was cut from the Sheffield Wednesday because, at 16, he was undersized, but he was able to carve out a career working his way up from the lower divisions. Dimitri Payet was cut from Le Havre at the same age; his former youth coach there said that "he was frail, weak and he lacked pace." He began his club career on Réunion Island. But countless players in similar situations never get another chance.
The system doesn't just shortchange late bloomers or those born late in the year, however. Players who go through puberty earlier than average can also wind up falling behind—it just happens later on in the process.
"What you see at the other end is, by 18, not all of the [early-maturing] players are making it through," says Hedges. "They're being caught up. They look really good young, because they are. They're miles ahead. They can be up to 20 percent more physically mature than their counterparts." But these players tend to neglect their technical development because they're used to dominating physically. When the rest of their age cohort catches up in physical maturity, Hedges says, "if you haven't given them the skills to deal with the other side of the game, then they don't look the player they looked at 13."
In short, according to the coaches and academy staff contacted for this article, academy washouts follow a pattern: late-developers are more frequently cut early on, while early developers are more frequently cut at the end of puberty. The league has yet to prove statistically that the pattern is related to the time of physical maturation, but a recent multi-year study in Switzerland supported the idea that late physical development was detrimental to a player's chances at higher-level success.
At Southampton, Bunce worked with Sean Cumming, a kinesiologist at Bath University and an expert in adolescent health and development. When Bunce moved to the Premier League in 2014, the two stayed in touch and began working together on a way to, in Bunce's words, make sure "everyone in the country had a better understanding of growth and maturation." They developed a program where kids would train with their age group at times, and at others, they would train and play in groups based on their level of physical maturity.
The practice is called bio banding, and it's a tool that rugby teams in New Zealand have used for years. Last year, after working with Cumming to develop a curriculum for bio-banding coaching education, Bunce hosted the Premier League's first bio-banded tournament for a handful of academy teams. He's currently working to expand the program, which is not yet mandatory. While some clubs like Norwich, Bournemouth, and Watford have quickly worked bio banding into their training schedules, others remain, in Bunce's words, "skeptical but very interested."
Part of the issue is a general resistance to new ideas inside the soccer community, which remains fairly insular. But it's not just about convincing skeptics to try something new. Bunce must also overcome a more widespread misunderstanding of the relationship (or lack thereof) between chronological age and physical maturity.
Take, for example, FIFA's youth tournaments. A few documented instances of cheating at international youth tournaments have sparked widespread suspicions of teams padding their rosters with over-age players. Each time it happens, it undermines the credibility of the event and puts organizers in a bind. Because not all athletes are able to provide birth certificates, FIFA and its members have been seeking other ways to prove a player's age.
Just last month, the Asian Football Confederation issued a triumphant press release about how it had done just that, successfully eliminating age cheating from its under-16 championship. By scanning players' wrists with an MRI and looking at the degree to which the growth plates in the wrist bones had closed, the AFC claimed its medical team could determine whether or not the player met the age requirements for the tournament.
Such age tests—looking at wrist bones is just one technique; using dental X-rays is another—seem reasonable at first glance. It is possible to show that a 16-year-old's skeletal structure, for example, would look much different than a 64-year-old's. But the studies FIFA says support these tests raise serious questions under closer scrutiny, as Dina Fine Maron has pointed out for Scientific American. Tim Cole, a medical statistician at the University of London, and the author of a paper critical of FIFA's age testing, told me the AFC's effort was "a joke." (The AFC refused comment on this story.)
"All of the methods seek to determine maturity, not to determine chronological age," says Noel Cameron, Professor of Human Biology in the School of Sport, Exercise and Health Sciences at Loughborough University. "That distinction is incredibly important, because we mature at our own rate, and our maturity is the result of a genetic process, which means that the timing with which we go through our maturity is an individual thing." (Although FIFA and the Premier League are focused on boys, age testing doesn't work on women either, who tend to develop at an even younger age. The median age of development also varies according to ethnicity.)
While seemingly ignored by FIFA in its fight against age cheating, this distinction between chronological age and maturity is precisely the point of bio-banding. The Premier League's bio-banding program uses the Khamis-Roche Method to determine maturity levels, by projecting a boy's likely adult height based on a function of his current age and height and the height of his parents. Bunce says the equation is accurate to within a few centimeters. The kids are then broken off into bio bands every fifth percentile or so, meaning kids who have reached between 90 and 95 percent of their predicted height are banded together, and then kids between 85 and 90 percent, and so on, usually into three or four groups.
Over the last two years, the Premier League has distributed standardized equipment and trained about 150 staff members at various academies on how to measure and assess physical maturity. "There isn't a rule or regulation that says you have to bio band or even look at growth and maturation," says Bunce, but the initiative has given clubs all the information they need to make a decision about whether and how to incorporate bio banding or at the least consider growth and maturation as a development variable. At Bournemouth, for example, players train in bio bands for six weeks at a time, before reverting to six weeks of training with traditional age groups. Bournemouth also does physical tests in banded groups, which can help determine if a kid is actually behind his peers in strength or simply operating on a different biological schedule.
There is not yet a bio banded league, and scheduling bio-banded matches is mostly up to clubs. There are informal discussions about incorporating bio banding into competitive fixtures in seasons to come, and Bunce hopes to put together nationwide tournaments in the near future.
The program is still in its infancy, in other words, but participating clubs are encouraged by the results from training and the matches in which they've taken part. After a banded match against Watford, Bournemouth surveyed its players and found that 100 percent of the early maturers thought the game had been more physically demanding. This makes sense. When your opponents are of the same physical maturity, they're much harder to push around. Instead of using their size, the players were forced to make sharper decisions and be faster on the ball. They had to focus on technique.
With the late bloomers, however, the coaches found some surprises, and not just at Bournemouth. Players who clubs thought were "quiet little shy kids, put within a much better maturity range, became leaders, much more vocal and passionate," Bunce says.
The mental aspect is important for technical development. Imagine you have a small, late-developing kid who has tons of tricks and skills, but in his age group competition he's constantly fighting a bigger, more mature player. "Well," Hedges says, "if for the hundredth, two hundredth, thousandth time he's done a great bit of skill and the guy's just put his arm across him and not alowed him to get past him, what's that going to do to him mentally, over time? He's going to go, 'I'm not successful doing that, so I'm going to stop doing that. I'm just going to give the ball backwards and sideways and keep possession.' You almost drum out of them that technical ability they've got."
In a bio-banded match, Hedges says, "it's a fair fight. In this scenario, he might be able to use his bit of skill and then get away from a player, hold him off. That's a physical duel won, and then he's out and moving. A lot of criticism of late-developers is that they can't sprint or don't run. Yeah, if they never get the chance to because they're always being held off by bigger boys, then he's never going to run more than two or three yards."
Exactly how bio banding will affect the next generation of Premier League stars is largely an exercise in wait and see. Whether bio banding changes youth development will also count on how many clubs use it, and Bunce's ability to win over the skeptics. Graham Mills, the Lead Youth Development Coach at Bournemouth, says it's still too early for them to use the bio banding data to help determine whether they keep or cut players. The club simply hasn't banded long enough. But it seems sure to play a role there and elsewhere in years to come.
No matter how widely bio banding is adopted by EPL clubs, nobody I spoke with thinks it will replace traditional academy age groups. After all, in the real world kids will have to learn to compete against players the size of Messi on the one hand, and Peter Crouch on the other. But bio banding, and controlling for growth spurts, looks set to become an important tool for evaluating talent.
"There is no reason as to why more early- and late-developing athletes cannot progress if they are optimally challenged," Cumming said by email. "What we need, and what most people in business aspire to are efficient and effective systems."
And the last thing a club wants to see is a player they invested in but ultimately cut from their academy line up years later for the opposition. Even worse is when it turns out he's a star.
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Brian Blickenstaff is a staff writer at VICE Sports. He tweets @BKBlick.