Paris - In the 2011 film "Moneyball", Brad Pitt plays Oakland Athletics general manager Billy Beane, who, as the head of a struggling baseball team, turns to data analysis of recruitment and training methods.
Beane was a trailblazer with his unconventional data metrics that flew in the face of baseball wisdom, and sparked a trend for in-depth statistical and data analysis.
That wave began to expand beyond American sport after the publication in 2003 of the Moneyball book, by Michael Lewis, drew attention to Beane's approach. Football was one of the sports that took notice.
"Once upon a time statistical analysis was used primarily on your own team performances and how to improve them," says Thomas Schmider, founder of statistics provider Prozone.
"Then statistics were used to help analyse the opponent. Now we are in a third phase which has started to involve recruitment."
Without analysis of his defensive statistics, N'Golo Kante might not have been spotted by Leicester City while the France international was still playing for Caen, and without him the Foxes may never have won their historic English Premier League title in 2016.
English clubs have led the way in the use of stats in football, with Manchester City and Liverpool each having a dozen "technical scouts" who comb through data banks while the traditional scouts criss-cross the globe watching players live.
Liverpool's former sporting director Damien Comolli, currently working as a pundit for French TV and radio, says having a scientific approach to recruitment "helps to reduce the percentage of failures".
"Beyond the qualitative analysis of each player we also have a statistical and quantitative analysis that very often enables better understanding of the characteristics or progression of a player," Francesco Vallone, head of scouting at Serie A club Roma, told AFP.
"These systems allow everyone to watch everyone, anywhere in the world. This increases the competition and that is why we must have the best organisation if we want to win."
Schmider, whose company was bought in 2015 by American business Stats, says that there is an arms race "to analyse more leagues, more matches, more stats".
According to the New York Times, Arsenal spent $4 million on acquiring data company StatDNA in 2012, to stop the US-based outfit from selling its services, which the Gunners were already using, to other clubs.
LIKE FOOTBALL MANAGER
Some clubs are even turning to Football Manager, the best-selling video game, with a spokesman for developer SI Games telling AFP that "several of the world's top clubs use our database as part of their scouting operations".
The football management simulator database of more than 350,000 footballers, each with their strengths and weaknesses, is "one of the largest in the world," says SI. It is built through a "network of more than 1,300 scouts".
"No one claims to have the perfect database, we are all human," says Benjamin, head researcher for Football Manager in France. In charge of Ligue 1 and 2, his job is to "assess a player's potential", determining their margin for improvement.
"We learn as much as we can, following matches on TV, talking with a network of correspondents as well as consulting fan forums and the press," says Ludovic, who follows France's regional leagues for Football Manager.
Both men do this in their spare time, on a voluntary basis.
"The more reliable the database, the more fun the game," says Benjamin.
And this research benefits the clubs as much as the video gamers.