WSL 20-21 - Player contribution analysis
The end of every season offers the possibility for teams to reflect on past fixtures. The focus shifts from preparing for the next game to looking back and analysing how well has the team performed and has it met expectations. Analysts go through every number possible to extract that valuable piece of information that will assist the coaching staff in the quest to make the team better during the coming season. In this article, the shot contribution model will be used, in conjunction with season data provided by FBRef, to analyse the 20–21 season and provide insights on how the teams performed in contributing to a shot.
The 20–21 Season in shot contribution
Figure 1 presents the team ranking for total shot contribution. It can be seen that Chelsea leads the league in that regard. There is no direct correlation between the shot contribution metric and the total shots accumulated by a given team. This can be explained by the fact that the shot contribution metric also punishes plays which do not convert promising chances into a shot and is explored in greater detail in Figure 2. Furthermore, the model takes into account only shots above a certain xG threshold, ignoring ones that are not deemed to be a threat to the goal. It also needs to be taken into account that at the end of the season teams can underperform or overperform.
Figure 2 shows a breakdown of the total shot contribution by position. Chelsea achieves its score by having a positive contribution for every position apart from the goalkeeper. It can be concluded that Chelsea is less wasteful when having a promising possession.
Looking at Arsenal and Manchester City a few interesting trends can be observed. Both teams possess a defence which progresses the ball into dangerous areas effectively, making up almost the entirety of the positive shot contribution for Arsenal and in Man City’s case, all of it. Their midfielders and strikers are shown to be wasteful and do not enjoy high numbers regarding this metric. Given that both teams are dominant on the ball and force teams to defend against them most of the time, midfielders more often than not receive the ball in tight spaces where progressing the ball is most challenging. Nevertheless, having a negative score means that both teams have been more wasteful with their possession than their competitors and addressing that can improve the teams’ chances of better results.
Another interesting finding is the high shot contribution for forwards for Manchester United and Bristol City. It can imply that forwards are often utilized in the build-up of the teams’ attacks.
After looking at the team performance, player contribution has been analysed. The analysis includes all players who have played at least 900 minutes so that it allows for the player to have had a considerable time to make an impact. Figures 3 and 4 show the highest shot contributors both in absolute terms and per 90 minutes.
Katie McCabe being the highest contributor shows Arsenal’s reliance on building from the left-fullback position. Having two defenders from Arsenal in the top 10 confirms the team’s emphasis on building from the back and also the quality of the ball that the defenders possess. Below Katie is Ebony Salmon, a forward from then relegated Bristol City. Playing for a struggling team, the player has had fewer opportunities to progress the ball into dangerous areas or to convert passes into shots. Nevertheless, the result shows that she was able to take the most out of the opportunities that were presented to her and equally important, give the ball away less in promising positions. She is then closely followed by the 2 leading goal scorers in the league — Sam Kerr and Viviannie Miedema. There are only 2 midfielders present in the top 10 — Inessa Kaagmman and Kenza Dali showing their efficacy in creating or converting shots. The contribution per 90’ shows makes Ebony Salmon the most valuable player in the league that season in terms of shot contribution. It also presents Chelsea’s efficacy by having three forwards.
Looking at the contribution per 90’ for each position serves as a confirmation of what has been discussed above.
The defenders’ top 10 is dominated by Arsenal and Manchester City. There is no Manchester City forwards in the top 10 which is not surprising given the previous figures. The top 10 midfielders statistic is dominated by mid-table teams, with 2 players from Chelsea, showing Chelsea’s midfield advantage over its main rivals. Interestingly, Chelsea’s goalkeeper, Carly Telford, has a significantly higher contribution considering other goalkeepers which can serve as an indication of the team utilizing the goalkeeper to progress the ball instead of the defenders. Lower numbers on contributions for defenders further confirm the observation.
Conclusion
The 2020–2021 WSL season has been analysed with the developed Markov model and players and teams have been compared by their shot contribution. Differences in the approach have been highlighted between Chelsea, Arsenal and Manchester City. The latter two utilise their defenders more for progressing the ball and building up dangerous attacks whereas Chelsea looks at a more direct approach. In absolute terms, Chelsea outperforms the two teams on the shot contribution metric by, in contrast, being less wasteful with promising possessions which is shown by their small amount of negative contribution.
A surprising discovery was Ebony Salmon. Despite playing for a team which got relegated, she managed to produce a league-high shot contribution score per 90 minutes which would go above top performers for league leaders like Sam Kerr and Vivianne Miedema.
Unlike conventional statistics which favour players from teams which create more and accumulate higher numbers, this metric highlights the part that a certain player plays in the shot creation of its team. It will put on display players who are over-relied on to create for their teams which could be used as an indication that a certain player is ready for a bigger challenge. Alternatively, information like the one presented in Figure 2 can highlight the advantages and shortcomings of a team to key-decision makers and assist with making quicker decisions. Something which in the long run can make the difference.
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