Overall, the current squad member of a big-5 league club who played the most domestic league games during his career is Leicester City’s goalkeeper Mark Schwarzer: 626 matches. Two other goalkeepers have already played more than 600 championship games over their career: Gianluigi Buffon (Juventus) and Kelvin Davis (Southampton).

Cristiano Ronaldo is second among players born in 1985 behind Bournemouth’s Simon Francis and ahead of Wayne Rooney. The top-3 tables are available in issue number 139 of the CES Football Observatory Big-5 Weekly Post. The analysis includes B-team matches.

The players listed below head the ranking for their age group.

Born on 1996 or after
Dele Alli, Tottenham, 98 matches
Born on 1995
Samu Castillejo, Villarreal, 129 matches
Born on 1994
Nathan Redmond, Norwich, 163 matches
Born on 1993
Romelu Lukaku, Everton, 210 matches
Born on 1992
Koke Resurrección, Atlético Madrid, 236 matches
Born on 1991
Eden Hazard, Chelsea, 277 matches
Born on 1990
James McCarthy, Everton, 295 matches
Born on 1989
Charlie Austin, Southampton, 320 matches
Born on 1988
Sergio Agüero, Manchester City, 368 matches
Born on 1987
Billy Jones, Sunderland, 395 matches
Born on 1986
James Milner, Liverpool, 410 matches
Born on 1985
Simon Francis, Bournemouth, 460 matches
Born on 1984
Wes Morgan, Leicester, 527 matches
Born on 1983
Jon Walters, Stoke City, 456 matches
Born on 1982
Rickie Lambert, West Bromwich, 597 matches
Born on 1981
Gareth Barry, Everton, 588 matches
Born on 1980
Sylvain Armand, Stade Rennais, 522 matches
Born on 1979
Massimo Maccarone, Empoli FC, 539 matches
Born on 1978
Gianluigi Buffon, Juventus, 612 matches
Born on 1977 or before
Mark Schwarzer, Leicester City FC, 626 matches

The U21 footballers listed below have played the highest percentage of minutes per position. Among them are notably two Schalke 04 players: Leon Goretzka and Maximilian Meyer. The latter footballer outranks his teammate Leroy Sané among attacking midfielders. The full tables are available here.

Goalkeepers

Gianluigi Donnarumma (Milan), born in 1999, 68.0%

Centre backs

Niklas Süle (Hoffenheim), born in 1995, 100.0%

Full backs

Héctor Bellerín (Arsenal), born in 1995, 92.3%

Defensive midfielders

Leon Goretzka (Schalke 04), born in 1995, 82.5%

Attacking midfielders

Maximilian Meyer (Schalke 04), born in 1995, 78.8%

Forwards

Anthony Martial (Manchester United/Monaco), born in 1995, 89.6%

The biggest performance gap was measured between Real Madrid and Rome: +32%. Atlético Madrid and Bayern Munich also performed significantly better than PSV Eindhoven and Juventus: +25%, respectively +23%. Manchester City and Barcelona outperformed Dinamo Kiev and Arsenal by 11%, while the performance level of Chelsea was 10% higher than that of Paris St-Germain.

According to the analysis of the CIES Football Observatory, the matches with the most uncertain outcome will oppose Gent and Wolfsburg (+3% for the Belgian club), as well as Benfica and Zenit St-Petersburg (+6% for the Portuguese side). Data used for the present research were provided by OptaPro. Click here for more information about the approach of the CIES Football Observatory for sustainable success.

Foreign players are much more numerous in Europe (47.7% of squads) and in the MLS (48.5%) than in Asia (17.9%) and South America (13.6%). Great discrepancies also exist according to position. While foreign footballers account for 34.9% of forwards, they only represent 20.5% of goalkeepers. The relative presence of foreign players among defenders and midfielders is around 25%.

From an age perspective, foreign footballers in the leagues studied are on average older than nationals: 27.1 years compared to 25.7. While only 13.2% of U21 footballers are foreigners, the latter represent 33.8% of players over 28 years of age. Nevertheless, the average age of first migration tends to diminish in relationship with the international recruitment of a greater number of very young players.

In six European leagues surveyed, more than half of teams are made up of foreign players: England, Belgium, Italy, Turkey, Portugal and Germany. At the opposite end of the spectrum, foreign players account for less than 10% of squads in Brazil, Uruguay, Venezuela, Costa Rica, Colombia, Argentina, Paraguay, Uzbekistan and Iran.

The study also warns the wealthiest clubs against the risk of abandoning the training of local players in favour of their import. The Report reminds that “all the clubs having left their mark on modern football in Europe (Real Madrid, Ajax, Bayern Munich, Milan, Manchester United, Barcelona) and elsewhere (Boca Juniors, River Plate, Santos, Flamengo) had several home-grown pillars, whose presence made a major contribution to their legendary status”.

The Report concludes that “talented players are born all over the world. What is missing in the first instance, is not so much talents, as a favourable context for their development. So as to encourage clubs worldwide not to take the easy road and fall into the trap of recklessly importing players and selling their souls to the market actors, training must be better protected and better paid”.

In 34 cases out of 49, the gap between the fee invested to recruit a big-5 league player and his estimated transfer value was less than 2 million €. The strong correlation between fees paid and predicted (76%) confirms the accuracy of the algorithm created from the analysis of more than 1,500 paying fee transfers occurred since 2010.

Our study allows us highlighting the payment of much higher or, more rarely, lower transfer compensations than fees paid in the recent past for players with similar characteristics. The inflation in transfer costs compared to the 11 previous transfer windows was 28%.

According to our estimates, the most over-paid player was Jackson Martínez: 42 million € instead of 18.2 (+23.8 million €). Among the five most over-paid footballers are another player transferred to China, Ramires (+10.8 million €), as well as three footballers signed by English Premier League clubs: Lewis Grabban (+7.8 million €), Timm Klose (+7.5) and Andros Townsend (+7.0).

The most under-paid player was also transferred between Premier League clubs: Jonjo Shelvey. According to our analysis, while the transfer value of the young English national A-team midfielder was 30.9 million €, Newcastle was able to sign him for "only" 16 million € (-14.9). The transfers of Mario Suárez to Watford and Augusto Fernández to Atlético Madrid were also cheaper than expected.

The figures for all big-5 league footballers transferred for money in January is available in issue number 136 of the Big-5 Weekly Post. For more information about the CIES Football Observatory approach, please refer to Monthly Reports number 6 and number 7. A transfer value calculator for big-5 league players is also freely available online.

Previous research from the CIES Football Observatory suggests that sticking on a core group of footballers often allows clubs obtaining top level results. No team who heads the table in its respective league used more than 24 players. This figure is 20 for Napoli, 22 for Leicester and Bayern Munich, 23 for Paris St-Germain and 24 for Barcelona.

Conversely, frequent line-up changes tend to reflect anxiety which is detrimental to the improvement of results. So far, clubs at the bottom of the table in their respective league on average fielded 26.0 players. This figure is 22.2 for clubs heading the table, 23.6 for the top three ranked teams per league and 25.3 at big-5 league level.