But, as their clubs are too wise to do so, football think tank CIES Football Observatory had to find out scientifically which football players are the most valuable. They considered these factors to evaluate players from Premier League, La Liga, Bundesliga, Serie A, and Ligue 1:
Player performance: The quality and consistency of their form
Player performance in relation to their club: Are they the star player?
International status: How established are they for their country?
Contract: Players with longer deals are more expensive
Age: Younger players command higher fees
Position: Goal scorers are more expensive than goalkeepers.