Issue number 137 of the Weekly Post presents analysis on the performance levels of Champions League last 16 round participants during the group stages. The study covers both defensive and attacking areas of play. This allows us to predict the most likely winners. 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% and +23% respectively.

Issue number 136 of the Weekly Post compares fees paid to sign big-5 league players during the January window with transfer values estimated on the basis of the algorithm exclusively developed by the CIES Football Observatory. In 34 cases out of 49, the difference between the fee invested to recruit a big-5 league player and his estimated transfer value was less than €2 million. The analysis also highlights that the inflation in transfer costs continues.

Manchester United have fielded the most players at English Premier League level since the start of the season. At the opposite end of the table is Arsenal. Arsène Wenger has only used 21 players so far, while Louis van Gaal has already fielded 28 footballers. The data for all clubs is available in issue number 135 of the Weekly Post. Previous research from the CIES Football Observatory suggests that maintaining a core group of footballers is more likely to allow clubs to achieve top level results.

Issue number 134 of the Weekly Post ranks players according to the level at which they outperformed their teammates since the start of the season. This allows us to highlight the outstanding performance levels of footballers who are, for the most part, not yet part of the most competitive teams, but could reach that level in the future. Several U23 players are in the top three rankings per league and position, such as Adam Masina (Bologna) and Leroy Sané (Schalke 04).

Issue number 113 of the Weekly Post ranks clubs according to their efficiency since the start of the season. The indicator of efficiency refers to the ability of teams to achieve the highest number of points with respect to their level of grip on the game and dangerousness. Stoke City is the most efficient club both in the English Premier League and at big-5 league level, ahead of Villarreal, Paris St-Germain and Hertha Berlin.

Issue number 132 of the Weekly Post presents data on the percentage of minutes played by footballers who represented a national A-team in 2015. At the top of the club table is Real Madrid, while the competition where active internationals play the highest percentage of minutes is the English Premier League. So far, footballers with national A-team caps in 2015 played 90% of domestic league minutes at Real Madrid.

Issue number 131 of the Weekly Post unveils the bi-annual list of the 100 big-5 league players with the highest transfer values, estimated according to the CIES Football Observatory exclusive algorithm. Lionel Messi heads the ranking ahead of teammate Neymar and Chelsea’s Eden Hazard. In fourth and fifth positions are Cristiano Ronaldo and Harry Kane. The estimated transfer value of Neymar, €153 million, is €59 million above that of June 2015.

If the Ballon d’or was awarded per position, the following big-5 league players would deserve to be named trophy winners according to their performances in 2015: Thiago Silva, Dani Alves, ?lkay Gündo?an, Santi Cazorla, Mesut Özil and Lionel Messi. Issue number 130 of the CIES Football Observatory Weekly Post presents the top 10 rankings per position, as well as the “dream teams” for both players over and under 23 years of age.

Current Manchester United and Manchester City squad members have played 120 national A-team matches in 2015. This is the record figure at big-5 league level. In third position is Chelsea (111), ahead of Paris St-Germain (106) and Barcelona (99). Seven out of the 10 top ranked clubs qualified for the Champions League knockout stages. The full set of results is presented in issue number 129 of the Weekly Post.

Issue number 128 of the Weekly Post analyses 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. This is the average date of birth of the typical citizen. The extreme values were recorded at Fiorentina (20 April) and Southampton (11 August). This confirms the existence of a selection bias in football, which favours players born in the first months of the year.

Issue number 127 of the Weekly Post presents data on the average transfer fee invested per player fielded. Four clubs stand apart: Real Madrid (€30.7 million), Manchester City (28.3), Manchester United (27.4) and Paris St-Germain (27.1). Only in two other clubs is the average transfer expenditure for players on the pitch above €20 million: Chelsea (21.9) and Barcelona (21.3). This figure is only €2.5 million for Leicester City.

Playing a significant number of matches from the start of a professional career is a key success factor for football players. Issue number 126 of the Weekly Post unveils the rankings of teams who played the most important role in the development of current big-5 league players. At the head of the European table is Real Madrid Castilla. Southampton contributed most to the development of English Premier League footballers.

Issue number 125 of the Weekly Post presents the rankings of clubs who have trained the most players under contract with teams in the five major European leagues. At the top of the table is Barcelona (44 players), ahead of Olympique Lyonnais (35) and Real Madrid (34). Munich 1860 heads the rankings of non-big-5 league clubs (18 players). The second division German club outranks River Plate (17) and Lens (16).

Issue number 124 of the Weekly Post reveals the rankings of the best performing players since the start of the big-5 league season. At the head of the tables for the five outfield positions considered are Otamendi (centre backs), Aurier (full backs), Cazorla (defensive midfielders), Özil (attacking midfielders) and Lewandowski (forwards). The rankings are based on a purely data-driven and objective methodology developed by the CIES Football Observatory research team.

Tottenham Hotspur tops the Premier League table of clubs who fielded on average the youngest players: 24.7 years. This is the fourth lowest figure at big-5 league level after Nice (24.1), Valencia (24.5) and Bayer Leverkusen (24.5). In second and third positions in the English Premier League rankings are Liverpool (25.5 years) and Newcastle (25.6). The data for all teams is available in issue number 123 of the Weekly Post.

Since the start of the season, 105 French footballers were fielded by foreign big-5 league clubs in domestic league matches. The second most represented origin abroad is Brazil (104 players). The most numerous contingent of French expatriates is to be found in England. Since the start of the season, 40 players from France have played in the English Premier League. All data is available in issue number 122 of the Weekly Post.

Issue number 121 of the Weekly Post shows that Chelsea FC is currently ranked thirteen positions below the ranking that transfer expenditure in signing squad members would have suggested. This is the biggest negative gap at both English Premier League and big-5 league level. Conversely, the most positive difference so far between financial and sporting ranking was measured by Leicester City: +12.

Issue number 120 of the Weekly Post presents the best performing outfield players since the start of the season, both in absolute terms and among U21 footballers. At the top of the absolute tables in the English Premier League are Laurent Koscielny (Arsenal) for centre backs, Cédric Soares (Southampton) for full backs, Santi Cazorla (Arsenal) for central midfielders, Mesut Özil (Arsenal) for attacking midfielders and Riyad Mahrez (Leicester) for forwards.