The analysis of the CIES Football Observatory is 100% data-driven from statistics provided by OptaPro. It takes into account the technical performance of players at big-5 league level since January 1st 2015 in six key areas of the game. More explanations are available in issue number 5 of the Monthly Report. From a broader perspective, the 7th Report presents the exclusive CIES Football Observatory approach for sustainable success.

Outfield players are divided into six positions: centre backs, full backs, defence-oriented central midfielders, attack-oriented central midfielders, attacking midfielders and forwards. Only footballers who played at least 2,250 minutes, equivalent to 25 full big-5 league matches, were included in the rankings.

On the basis of our analysis, the CIES Football Observatory dream team (4-2-3-1) is composed as follows: Neuer; D. Alves, T. Silva, Chiellini, Monreal; Gündogan, Cazorla; Özil, de Bruyne, Hazard; Messi. The dream team for U23 players, born after 1st January 1993, is composed as such: Karius; Bellerín, Umiti, Varane, Wendell; Tolisso, Pogba; B. Silva, Barkley, F. Anderson; Dybala.

Despite top level performances, several players do not appear in the tables as they were not fielded for at least 2,250 minutes in big-5 league games in 2015. This is notably the case of Z. Ibrahimovi?, M. Salah and S. Agüero among forwards; D. Silva, J. Navas and D. Perotti among attacking midfielders; M. Verratti, Y. Touré and A. Ramsey among central midfielders; L. Kurzawa, A. Kolarov and J. Alba among full backs; as well as D. Luiz, J. Boateng and D. Alaba among centre backs.

For more information, please contact us at football.observatory@cies.ch.

Seven out of the 10 top ranked clubs qualified for the Champions League knockout stage. The only exceptions are Manchester United, Tottenham Hotspur and Inter Milan. The last two clubs did not even participate in the competition. However, the Italian side is currently at the top of the Serie A table.

Real Madrid is the team with the most footballers with national A-team caps in 2015: 19 players. At second position is Manchester United (18). Louis van Gaal’s team outranks Chelsea, Tottenham and Juventus (17 players each). In total, Manchester United players represented 10 national selections. Sergio Romero played more games for Argentina (13) than for Manchester United (4).

List of players

• Sergio Romero, 13 matches for Argentina
• Marcos Rojo, 11 matches for Argentina
• M. Darmian, 10 matches for Italy
• Daley Blind, 9 matches for the Netherlands
• Wayne Rooney, 8 matches for England
• Morgan Schneiderlin, 8 matches for France
• Memphis Depay, 8 matches for the Netherlands
• Phil Jones, 7 matches for England
• Bastian Schweinsteiger, 6 matches for Germany
• Chris Smalling, 6 matches for England
• Anthony Martial, 6 matches for France
• Marouane Fellaini, 6 matches for Belgium
• Patrick McNair, 5 matches for Northern Ireland
• Antonio Valencia, 4 matches for Ecuador
• Juan Mata, 4 matches for Spain
• David De Gea, 4 matches for Spain
• Michael Carrick, 3 matches for England
• Luke Shaw, 2 matches for England

Nowadays, throughout Europe, players with the disadvantages of being born in the last months of the year and of later physical development have little chance of pursuing a career at a high level. The authors recommend to organisations in charge of the development of youth players and the game to “take the question of the relative age effect seriously”.

According to the Report, the limiting of the selection bias linked to the date of birth and to the level of physical development would reinforce meritocracy in football. Over the long term, such a step forward would be beneficial not only to the level of spectacle that teams are able to provide, but also on the level of balance of competitions.

English players are the only ones born on average after July 1st, the average date of birth of a typical citizen. This can be explained by the fact that age classes in English football are based on the cut-off date used by the school system, the 1st September, and not the 1st January as in other countries. Consequently, the least represented players among English professional footballers are those born in August and not in December as in the 30 other associations surveyed.

Issue number 128 of the Big-5 Weekly Post presents the data on the average day of birth of players for each club of the five major European leagues. In 23 teams only, this date is after July 1st. The extreme values were recorded at Fiorentina (20 April) and Southampton (11 August).

In two other clubs only, the average transfer expenditure for player on the pitch is above 20 million €: Chelsea (21.9) and Barcelona (21.3). This figure goes down to 16.1 million € at Arsenal, 15.8 million € at Liverpool, 11.1 million € at Tottenham … and 2.5 million € for Leicester City.

On average, Bayern Munich (15.4 million €) and Juventus (14.4 million €) also spent only half per player than Real Madrid, Manchester City, Manchester United and Paris St-Germain. This finding highlights the great discrepancies existing up to the very top of the football pyramid.

All the data is available here.

In total, the 2,165 footballers fielded so far by big-5 league teams have played in 1,276 clubs from the start of their career at adult level to their 23rd birthday. At the top of the table of teams having contributed most to the development of these players is Real Madrid Castilla. Up until 23 years of age, 45 footballers under contract with big-5 league teams have played for the team currently coached by Zinédine Zidane. Among them, we notably find Juan Mata (Manchester United), Alvaro Negredo (Valencia) and Roberto Soldado (Villarreal).

For comparability reasons, the player development index only considers domestic league games. A match played before the age of 21 is weighted double with respect to a game played between 21 and 23 years of age. Moreover, the values are weighted according to the current employment rate of players in order to give more weight to teams having developed the most fielded footballers.

The team who contributed most to the development of Premier League players is Southampton, followed by Aston Villa and Dutch side Ajax Amsterdam. Chelsea and Everton also rank in the top five positions.

At the top of the tables in the remaining big-5 leagues are Empoli for Italian Serie A players, Bayer Leverkusen for German Bundesliga, Barcelona B for Spanish Liga and Olympique Lyonnais for French Ligue 1 footballers. Issue number 126 of the CIES Football Observatory Big-5 Weekly Post presents the data for the top 40 clubs per league.

The player development index could be particularly useful for leagues, national associations and international football governing bodies to set up systems of financial equalisation and/or reward mechanisms incentivising more teams to promote both the training and fielding of young talents. Over the long term, this would have a positive effect on football as a whole.

For more information, please contact us at football.observatory@cies.ch

The CIES Football Observatory Digital Atlas presents league and club rankings for eight indicators:

• Average age: the oldest top division league in Europe is Turkey (27.3 years), while the youngest is Croatia (23.9 years). At club level, Chievo Verona is composed of the oldest players (30.6 years). Hajduk Split and Senica have the youngest squad (22.1 years).

• Average height: the tallest top division leagues at European level are in Germany and Croatia (183.3 cm). The shortest players are to be found in Israel (180.1 cm). There is a 9 cm gap between the tallest and shortest club: Wolfsburg (187.0 cm) and Ludogorets Razgrad (178.0 cm).

• Average stay: the most stable league from a player turnover perspective is England. Squad members have been in the first team of their employer team for 2.82 years on average. At the opposite end of the table is Serbia (1.71 years). The most and least stable clubs are CSKA Moskow (5.7 years) and Chornomorets Odessa (1.2 years).

• New signings: clubs in Romania signed the most players since January 1st 2015: 14 per club on average. At the other end of the spectrum is Sweden (7.4 players). At club level, the record high was recorded at Bologna (23 players), while the record low was measured for Karpaty Lviv and Metalurg Zaporizhya (1 player).

• Debutants: on average, European top division clubs launched 1.04 players without previous experience in the professional game: from 2.29 in Ukraine to 0.13 in Greece. Metalurg Zaporizhya holds the record at club level with 11 debutants. However, they are currently at the bottom of the Ukrainian Premier League table.

• Club-trained: the top division league in Belarus has the highest percentage of club-trained players (34.0%). Inversely, in Turkey, players who have been in their employer club for at least three seasons between the ages of 15 and 21 only account for 8.3% of squad members. The record high at club level was observed at Gomel (91.7%). More information is presented in the ninth edition of the CIES Football Observatory Monthly Report.

• Expatriates: the top division league with the highest percentage of expatriate players is that of Cyprus (66.4%). The lowest proportion of expatriates was recorded in Serbia (15.7%). Expatriate footballers account for up to 88.0% of squad members at Slovenian side NK Zavr?. Only three teams out of 460 have no expatriates: HIFK Helsinki, FK Gomel and FK P?íbram.

• Active internationals: the English Premier League gathers the highest percentage of players with national A-team caps since the start of the season (41.4%). This percentage is only 2.0% in Slovenia. The club composed of the greatest proportion of active internationals is Manchester United (72.0%).