The Manchester City fanbase has lately raised doubts over Ederson's shot-stopping competence, and some have even gone as far as to suggest that he is 'overrated'. Moreover, a handful of critics believe the football world has deemed him to be 'world-class' due to the Brazilian's exceptional ball-distributing ability while overlooking his relative incapacity to save shots.
Are those claims valid? Data will provide an answer.
Explore more articles Unravelling Chelsea's dance with Financial Fair Play
Before getting into the numbers, it is handy to understand how goalkeepers can be statistically measured.
The most basic metric is the save percentage. It simply calculates the percentage of total shots saved. It is unwise to judge the proficiency of a goalkeeper by only looking at this statistic, as it does not reveal the complete picture.
In the 2021/22 Premier League campaign, Illan Meslier of Leeds United finished the season with a save percentage of 66.4%, whereas Huge Lloris of Tottenham Hotspur recorded a 72.3%. When only looking at those figures, you may think the 2018 World Cup winner had a better season. However, Meslier faced 83 more shots than Lloris - revealing that Meslier had more opportunities of conceding goals. So does your opinion remain the same, or do you feel more analysis and context are required?
The upgraded model later adopted by analysts was the expected goals against (xGA) framework. The difference between the goals allowed and xG faced is calculated to find the 'actual goals prevented'.
For example, if a player concedes 10 goals from an xGA faced of 12, the model suggests that the goalkeeper has let in 2 fewer goals than expected. On the contrary, if he conceded 16, the framework implies he let in 4 more goals than expected.
The model was refined later by adjusting for the quality of shots to find the 'post-shot xG faced' - the calculation of which was well-explained in an article by 'The Football Critic'.
"A robust Expected Goals model takes the shot position, the angle of the shot in reference to the goal, whether the effort was a header or a shot (headers are, notoriously, scored less), and whether there are defenders between the player and the goal. These models are based upon tens of thousands of shots gathered over an extensive period of time".
(Value of xG when taking shots from different areas of the pitch)
"This provides a valuation for every shot based on the historical precedent of the likelihood of shots from that position and those variables remaining true. But what Expected Goals doesn't do is establish what happens to the shot when the ball has left the player's foot. What Post-Shot Expected Goals does is take the shot quality (i.e. what would be an xG high-tariff chance) and combine it with what actually happened - the destiny of the shot".
If you did not understand that description, in the most simple words, the post-shot xG adjusts the value of a shot for its placement quality. Therefore, shots heading to the top corner have a higher post-shot xG value than one directed straight to the goalkeeper, as the former is harder to save than the latter.
So, measuring the post-shot xG faced computes the caliber of shots goalkeepers face.
Now that we have addressed the ambiguous data language, let us move on to the analysis methodology.
Since the post-shot xG faced by a goalkeeper is the most accurate metric readily available online to determine the quality of the shot faced, we will compare that value to the goals conceded, thereby determining the number of goals saved (according to the model).
(Post-shot xG +/- or "goals saved" performance by Ederson for Manchester City in six seasons - 2017/18 to 2022/23)
(*value correct as of 1st March, 2023)
Without further context, his performances neither seem impressive nor disastrous for most years - as a deviation of plus or minus a goal shows that he has delivered close to expectations, with a slight under or overperformance. And this is true for three seasons (2017/18, 2018/19, and 2021/22). Like any other footballer, he experienced his highs (2019/20) and is going through his lows (2022/23*).
Nevertheless, there are other variables to assess when analyzing a goalkeeper's shot-stopping ability.
Playing for a possession-dominant Manchester City side means that the goalkeeper is bound to face fewer shots than an average Premier League team. Which therefore results in having to save fewer but higher quality chances than the average Premier League goalkeeper, right?
That is what logic tells us. But what about the numbers?
(Number of shots on target faced by Ederson per 90 minutes compared to the Premier League average )
(*value correct as of 1st March, 2023)
(Quality of shots faced by Ederson compared to the rest of the leagues average)
(*value correct as of 1st March, 2023)
The graphs above reveal intriguing actualities.
The first chart proves the obvious - an average Premier League goalkeeper faces a higher volume of shots on target than the Manchester City no.31.
But the second graph contemplates the prior assumption about Ederson facing higher-quality shots, as the numbers show otherwise. There is no consistency of Ederson encountering a higher quality of shot per match as reflected by the irregular convergence and divergence of the two lines.
So, what does it all say?
The 'actual goals saved' numbers suggest that Ederson's performances are usually around, if not better, than expectations apart from the ongoing season. And that is more than good enough.
When comparing Ederson's performances over the years to the other elite goalkeepers across Europe, he is relatively consistent, as shown by the steady numbers - neither overachieving nor disappointing (apart from the ongoing campaign).
('Goals saved' by some of the top goalkeepers across Europe in their respective domestic leagues)
(*values correct as of March 10, 2023)
But then again, considering Ederson faces a significantly lower volume of shots, he is exposed to fewer goal-saving opportunities than his peers.
(Data from StatsBomb via FBref)
(*values correct as of March 10, 2023)
So, as Ederson is exposed to fewer chances to display his shot-stopping ability, statistically, the Brazilian does not record eye-watering numbers. Instead, he meets expectations. And although that may not be glamorous, his performances can be relied on by a team that competes on all fronts every season.
The recent criticisms have transpired at a time when Ederson, like any other footballer, is facing a turbulent spell of form - as shown by the PS xG +/- graphs.
But this should not taint his ability and achievements over the past six years.
We may never know how well Ederson would do in a team where he has to face more shots than he is used to at City. But as long as the twenty-nine-year-old maintains his standard behind the sticks, the Brazilian will continue lifting major trophies at one of the best clubs in Europe.
Comments