Corner kicks in the Belgian First Division A 2019/20 – data analysis

Corner kicks are a vital part of football. Whilst the corner kick is sometimes misconceived due to an overinflated perception of success, the set-piece can differentiate between winning, losing and drawing outcomes in an instant, therefore, highlighting the need to repeatedly investigate corners. Studies have shown corners to result in a goal in as little as 2.2% of occasions in the EPL La Liga and UEFA Champions League. The low success rate of corners mean that a successful corner kick routine and delivery have increased importance, given teams can significantly enhance their chances or scoring or preventing the opposing team from scoring through effective corner kick performance. For this reason,  corner and set-piece analysis is constantly being produced within football clubs and in the wider football analysis world. The importance of corner kicks can be further emphasised by the recent introduction of specialist corner and set-piece coaches and analysts within the game.

This corner kick data analysis will focus upon offensive corner statistics from the  Belgian First Division A in 2019/20. This piece will help to determine trends along with frequent, successful and effective routines for teams in the league. The piece will act as an introductory study into corner kicks in the Belgian league, leading to the potential for a more detailed analysis of the strategies and routines identified by the data. This piece will also help to preview the 2020/21 season by predicting which teams may be the leaders in corner kick execution, as well as teams who need to improve within this area.

League overview

In the 2019/20 season in the Belgian league, 2030 corners were taken which resulted in 69 goals, a conversion rate of 3.39%, which is higher than previous studies of an academic and applied notion on different leagues and competitions. The league average resulted in 133.8 corners per team, 21.8 shots from such corners, a shot in 16.29% of corners, a total xG of 2.45, and an xG per shot of 0.11. This analysis further reinforces the difficulty of delivering and creating chances from corner kicks. The average number of goals scored from corners was 4.31 per team, an overperformance of the xG. The low xG may be due to the typical headed nature of corner related shots. Headed shots are naturally more difficult to score from and so earn a lower xG. However, the overperformance may be due to the mechanism of the corner. Usually, the ball is crossed into the area with pace, therefore, any headed shot to flick the ball or redirection of the ball is difficult for the goalkeeper to save. This is due to the pace on the ball, changes in direction, the low perception, and reaction time given there are multiple players trying to attack and defend within close proximity in the 18-yard box.

The analysis above is justified in terms of a breakdown of the target zones. The most popular delivery zone is near post. The most effective target zone in terms of percentage of corners resulting in shots was the penalty area with a shot in 29.16% of corners to that area, a diagram of the target zones can be found below. However, the penalty area zone is not the most dangerous area to take a shot from. Statistically, the penalty area zone provides the highest chance of a shot, but this is likely due to the fact the penalty box zone is the largest, easiest to deliver to, and attack the ball from. The penalty area zone does not deliver the highest xG in terms of chance quality per shot, most likely due to the fact it is further away from the goal than other zones. The most effective in terms of xG per shot was the GK zone (0.19), commonly known as the six-yard box. Whilst the most shots come from the penalty box zone, the highest quality shots come from the GK zone due to the shortened distance between the attacker and the goal, therefore providing a closer target for the attacker and less time for the goalkeeper to react, therefore, increasing the expectancy of goals after shots in this area.

Whilst the league average was 4.31 goals from corners in the 2019/20 season, different teams in the league performed above or below this average. Ranked top for corner goals were Club Brugge, which may provide further justification of their offensive quality after the team also won the league. Ranked bottom were Oostende, which may provide additional reinforcement of their attacking frailties after they finished 15th out of 16 teams. However, the discussion that these statistics may reinforce team quality needs to be stressed. This is because, through previous knowledge, we know that corners are influenced by possession, territory and playing style. If a team has a large amount of possession, in high and wide areas, and is frequently taking shots, making crosses or taking on defenders, they are likely to receive more corner kick opportunities to score from. On the flip side, teams with low possession, a deeper and narrower average position, and the inability to take large amounts of shots, crosses or take-ons will earn fewer corners and therefore fewer chances to score from corners. Let’s see if this theory is true within the Belgian league.

The average final league position of teams who performed above the average corner goal tally is 4.2, a successfully low average ranking given there are 16 teams in the league. For those that underperform, the average finishing position is 9.25, a higher, less successful ranking. This, along with the scatterplot below, shows that the more successful teams in the league in generally score more goals from corners. But why?