Unpacking Chelsea's goalkeeping conundrum: Stick or switch strategy?

Chelsea look set for a busy summer transfer window, with The Telegraph reporting that the Sporting Directors and recruitment team will proactively seek to strengthen various positions through acquisitions.

One issue Chelsea will address is goalkeeper, which comes as a surprise, having purchased two 'keepers, Đorđe Petrović and Robert Sánchez, only last summer.

The Pride of London will explore the rationale behind the West London club's dissatisfaction with their current options and the profile type they will search for.

Subpar Shot-Saving Performance

The foremost measure of a goalkeeper's performance is their ability to save shots. However, we are not referring to basic metrics like saves made or goals conceded since it does not account for factors such as shot quality that can significantly influence a goalkeeper's ability to execute a save.

The Post-Shot xG +/- (PSxG +/-) is an advanced statistic that provides a better picture of a goalkeeper's performance in 'preventing goals'.

It works similarly to gauging the shooting performance of attackers by comparing goals scored to expected goals (xG), with any positive or negative value indicating over or underperformance.

For goalkeepers, the goals conceded figure is weighted against the quality of shots faced - measured by the PSxG metric that computes the various determinants of shot quality, like location, distance, and others. A positive or negative difference, therefore, suggests an over or underperformance.

However, the PSxG model is imperfect, as shot volume and luck can skew a goalkeeper's output. Nevertheless, it is one of the best metrics available to evaluate player performance.

The Chelsea goalkeepers' PSxG +/- output paints a worrying picture for the club, as the duo lies in the group of Premier League goalkeepers that have underperformed.

The statistic suggests that Petrović was severely disappointing, while Sánchez was also uninspiring. However, this is only one of the reasons for Chelsea's concern in the goalkeeping department.

On-Ball Expertise

Enzo Maresca, Chelsea's incoming head coach for the 2024/25 season and beyond, adopts a possession-based system that aims to dominate the ball - requiring the goalkeeper to be comfortable with the ball at his feet.

Mads Hermansen was purchased by Leicester City for that exact reason ahead of the 2023/24 Championship campaign to provide Maresca the on-ball assurance that he demands.

However, Chelsea's goalkeeper duo has not yet demonstrated whether they can fulfill that role in the long term.

Sánchez was bought in from Brighton for that purpose. However, he proved unreliable on numerous occasions in the previous campaign. Petrović, on the other hand, seemed to be the typical "no-nonsense" goalkeeper in possession but improved over the season. Nevertheless, he does not pose as an elite-level distributor as Maresca desires.

Some of these differences are echoed in the data, with Hermansen launching fewer passes and goal-kicks than the Chelsea duo - indicating his ability and tendency to play shorter passes to help his team in the build-up. Moreover, the Leicester goalkeeper also posts a better pass completion rate in short, medium, and long distances.

Therefore, any incoming goalkeeper should be a better distributor and have the composure to help Chelsea in the first build-up phases.

Sweeper 'Keeper Duties

When analyzing the numbers for the three players, in terms of sweeper-keeper responsibilities, Hermansen and Sánchez perform similarly. Petrović's numbers reveal his hesitancy to step out of his line. The eye test reflects the same, as he looked shaky during the season, producing many nervy moments for the Blues.

Therefore, Chelsea will require a player capable of executing sweeper-keeper duties to allow Maresca to employ a high defensive line.

Stick or Twist?

Sánchez offers the better alternative between Chelsea's pair when considering the on-ball and shot-stopping metrics but has not yet proved to be a consistent performer. Nevertheless, Petrović, at age 24, still has unfulfilled potential, and the 2023/24 season revealed that he can develop into a top-class goalkeeper, delivering many breathtaking moments.

Judging by the various reports, the West London club seems unlikely to maintain patience and has decided to address the goalkeeping concerns through another addition.

Although there are no concrete reports on who the candidate will be, despite a few rumors, the Chelsea recruitment team will undoubtedly scout for someone who ticks all three boxes outlined in this article.