Past his peak? Assessing goalkeeper performance by age and Manuel Neuer vs Alexander Nübel

In 2020/21, Bayern Munich will enter a new era: for the first time in his Bayern career, Manuel Neuer will face competition for his starting position. Alexander Nübel’s arrival has been met with some skepticism by Bayern fans. Neuer is still performing at a high level, and many feel that he still has plenty to offer in the near future. However, at 33 years old, Neuer isn’t getting any younger. The question is: How old is 33 for a goalkeeper?

High-profile cases like Gianluigi Buffon, Iker Casillas, Neville Southall, and Bayern Munich’s own Oliver Kahn have led fans to view goalkeepers as ageless wonders, but these examples do not necessarily represent wider trends, and the physical demands on modern goalkeepers are greater than in previous generations. It is therefore reasonable to question whether these past examples apply to modern goalkeeping.

Timing the peak

Previous studies suggests that footballers reach their peak earlier than expected. Research studying the average age of Champions League players from 1992/93 — 2017/18 and domestic leagues in Europe from 2010/11 — 2014/15 has found that footballers reach their peak at age 25—27, while goalkeepers tend to reach their peak later in their career and often last into their early 30s. Further research by Michael Caley and Mark Taylor has also found that footballers at various positions reach their peak in their mid 20s and decline when they enter their 30s.

The research detailed above is helpful, but given recent advances in measuring goalkeeper performance, there is an opportunity to test this question further. In this article, I will examine the age that goalkeepers reach their prime, and how long that prime lasts, by using playing time and performance measures. I will measure the performance and playing time of goalkeepers in the big five European leagues (Premier League, La Liga, Bundesliga, Serie A, and Ligue 1) from 2009/10 — 2019/20, using data provided by FBref and Understat.

Evaluating goalkeepers’ peak by playing time

The simplest and perhaps most effective measure of a player’s peak is his playing time. Playing time represents availability, performance, and value to the team. Figure 1 presents the average number of minutes played per season by goalkeeper-age from 2009/10 — 2019/20.

Goalkeepers play, on average, more than 1500 minutes per season from age 24 to 31 and begin to decline slowly at age 31+. This gradual decline moreover captures only a fraction of goalkeepers’ average true decline, because it does not account for goalkeepers who retire from football. Figure 2 plots the number of goalkeepers registered as members of first-team squads according to their age.

The age of first-team goalkeepers exhibits a steeper decline than age by playing time, suggesting that there is a significant drop off from 30+. Figures 1 and 2 thus seem to support the idea that football players peak in their mid 30s, while goalkeepers maintain their peak into their early 30s.

Evaluating goalkeepers’ peak by performance

Playing time is informative, but an alternative approach to measuring an athlete’s prime is to scrutinize his performance level over time. I will use two primary methods for measuring goalkeeper performance. The first relies on post-shot expected goals (PSxG), which measures a the location, trajectory, and speed of a shot after it has been taken to estimates the probability of the shot resulting in a goal.

Calculating the difference between the PSxG a goalkeeper has faced and the actual number of goals he has conceded (PSxG +/-) produces a value that may reflect goalkeeper performance. Positive values indicate the goalkeeper has saved shots that had a high probability of ending in goals, while negative values suggest the opposite. Figure 3 plots PSxG +/- by goalkeeper-age from ages 18 to 40 for all goalkeepers who played a minimum of 1350 minutes from 2017/18 to 2019/20 (the years for which the data is available).

Goalkeeper performance peaks from age 23 to 27, then declines gradually until around the age of 32, when it begins to tail off quickly. Goalkeepers in their 30s perform worse than those in their mid to late 20s, showing that even those goalkeepers who continue to play significant minutes beyond their expected peaks are less effective. It seems reasonable to assume that the keepers who are dropped and/or retire are also worse than their counterparts that continue to start.

The second approach to measuring goalkeeper performance is goals saved above average (GSAA). GSAA uses the league-average save percentage to calculate the average number of goals that would be conceded when facing the number of shots a particular keeper has faced, and compares this to the actual number of goals conceded to produce a plus/minus value reflecting the number of goals that a keeper has saved (or conceded) compared to the league average goalkeeper. Positive values reflect above-average goalkeeping, while negative values reflect below-average goalkeeping. Figure 4 plots the GSAA% for goalkeepers by age group.

In this case, there is a steep decline from age 30 – 32 onwards, and as with PSxG +/-, these numbers will be suppressed by differences in playing time.

Similar to the playing-time results, goalkeepers appear to peak in their mid 20s and maintain this level into their early 30s, before declining pretty quickly. Few goalkeepers play into their mid to late 30s, and of those, even fewer perform to the high standards set by their younger counterparts.

Comparing Manuel Neuer’s performances with the rest of Europe

Having established that goalkeepers peak earlier than expected, we now may apply these assessment methods to Manuel Neuer’s performances to test whether we can observe the same decline as he has aged.

First, I looked at the best goalkeepers in Europe, based on PSxG/90 and GSAA% from 2017/18 — 2019/20, plotted below in Figure 5:

Manuel Neuer doesn’t feature in this comparison of the performance of Europe’s goalkeepers, but the reason is largely circumstantial. Neuer suffered serious injuries in 2017/18 and spent 2018/19 regaining his form. It has only been in this season that his form has been consistent enough to expect him to feature among Europe’s best.

In order to better define Neuer’s peak and to compare his performances over time and with the rest of Europe, I calculated GSAA % for goalkeepers in Europe from 2009/10 — 2019/20. Figure 6 plots these results.

Neuer spent five seasons among the very best goalkeepers in Europe in terms of shot-stopping. Factoring in his qualities as a sweeper and his excellent passing range, it is easy to see why he was widely regarded as the best goalkeeper in the world. Unfortunately, he suffered injuries in 2017/18 and he has thus far been unable to reach the high standards he set earlier in his career. Although he appears to have improved in 2019/20, his GSAA% remains significantly worse than it was in his prime.

Given Neuer’s age, the fact he has not performed at his peak for three seasons now, and the fact his performances correspond with the expected decline of a goalkeeper approaching his mid-30s, it is possible that this is evidence of a gradual decline. Of course, a gradual decline from a peak as high as Neuer’s does not mean he cannot be a top goalkeeper for the next few seasons — but is enough for Bayern?

Neuer & Nübel compared with the rest of the Bundesliga

Using data from the current season, we can compare also Neuer and Nübel with the rest of the Bundesliga. That enables us to frame both players in relative terms and consider the potential for competition between the two in the near future. Figure 7 plots the top 15 keepers in the league (by minutes played) on a number of metrics.

Using GSAA and PSxG +/- we can judge both players in terms of shot-stopping. Nübel is one of the best goalkeepers in the league in this regard, while Neuer hovers around the middle of the pack. To some extent, Neuer’s numbers will be suppressed by the fewer number of shots that Bayern face, particularly in the case of GSAA, but a negative PSxG +/- isn’t great.

Focusing purely on shot-stopping, however, would do a disservice to Manuel Neuer’s game. Neuer was a pioneer of the modern generation of goalkeepers who are quick off the goal line and perfectly capable of playing with the ball at their feet. The OPA and xGBuildup plots above demonstrate how well-rounded Neuer is, even at age 33. He is still very active outside his own penalty area, and he is capable of contributing to attacking play in a way few other keepers can, as demonstrated by his average of 0.32 xGBuildup/90. When compared with goalkeepers around Europe that have played at least 1000 minutes, only Alisson and Ederson come close to that kind of production, averaging 0.28 and 0.27 respectively.

Neuer’s well-rounded game becomes even more obvious when you look at his passing range. Figure 8 plots these goalkeepers according to their long ball accuracy.

Again, Neuer leads the pack by some distance, almost doubling Nübel’s completion percentage. Nübel’s passing numbers are much more limited than Neuer’s, but this is in part due to Schalke’s playing style. He averages 43.2 touches per game to Neuer’s 45.2, while his pass attempts make up 7% of Schalke’s total pass attempts, compared with Neuer’s 5.2%. It is unlikely he will ever possess the passing range and close control that Neuer boasts, but he can still contribute with the ball at his feet.

When you compare the performance of the two goalkeepers, it is clear that they fit slightly different profiles. Figure 9 compares Neuer and Nübel directly.

Overall, Neuer is the more well-rounded goalkeeper, and it is clear that he is still playing at a high level. His negative PSxG +/- is a little concerning, but his OPA and xGBuildup highlight his overall quality. Nübel has a limited passing range, but excels in every other category, even outperforming Neuer in terms of shot-stopping.

Conclusion

It seems clear that Neuer still has plenty to give. But at age 33, having suffered two broken bones in his foot and showing some signs of decline, it seems sensible on Bayern’s part to prepare for life after Neuer. He is undoubtedly a club legend and one of the greatest goalkeepers in history. He surely has the capacity to adjust his game in order to slow the negative effects of his physical decline. But for a goalkeeper whose legacy has been built on his capacity to contribute to all facets of the game and all over the pitch, that will be difficult.

Nübel is a gifted keeper and an impressive athlete, and he possesses remarkable reflexes and goalkeeping instincts. His shot-stopping is excellent, and he is quick enough off his line to be active outside his own penalty area. His passing range is no match for Neuer’s, but he is still capable of contributing to buildup play. Further, by transferring to Bayern, he will have the opportunity to learn from Neuer, to refine his decision-making, and to develop his abilities with the ball at his feet. Nübel’s own peak may be only a few years away, while Neuer is fighting a battle against aging that everyone eventually loses. It may not be long before we witness the changing of the guard.