Carlos Alcaraz remains one of the very best tennis players in the world. Even after spending several months away from competition due to injury, his results since returning have been impressive. He has continued to win matches and compete at the highest level, emphasizing this by winning the Japan open.
Yet a question has emerged around one particular aspect of his game: has his serve become less effective since his return to the sport?
At first glance, his results might suggest that little has changed. Winning 11 out of 13 matches on hardcourt both before as well as after returning from injury. But winning matches does not always indicate a specific performance level.
A player as complete as Alcaraz can compensate for weaknesses in one area of his game through exceptional performance elsewhere. So rather than looking at match results alone, we wanted to examine the underlying numbers. Has Alcaraz's service performance actually declined? And if so, how significant is that decline?
To investigate, we turned to the Tennis AIQ historical database.
Comparing 26 hardcourt matches
For this analysis, we selected two groups of matches: Alcaraz's last 13 hardcourt matches before his injury and his first 13 hardcourt matches after returning to competition.
Restricting the analysis to hardcourt matches is important. Service effectiveness can vary significantly between surfaces, and including clay or grass matches could distort the comparison.
For each match, we examined three variables:
1) Alcaraz's Service Points Won (SPW%) measures the percentage of points he won on his own serve.
2) Opponent Service Points Won (SPW%) measures the percentage of service points won by his opponent, providing an indication of Alcaraz's effectiveness on return.
3) Opponent Hardcourt Skill Rating measures the opponent's strength according to the historical Tennis AIQ model at the time of the match.
The third variable is particularly important. A player winning 70% of his service points against one of the strongest returners in the world is not necessarily equivalent to winning 70% against a much weaker opponent. By including the opponents' Skill Ratings, we can place the raw service statistics in a more meaningful competitive context.
The first finding: a substantial decline on serve
The first graph compares Alcaraz's service performance before and after his injury.
Each dot in the graph represents one hardcourt match. The horizontal axis shows Alcaraz's percentage of service points won, while the vertical axis shows his opponent's historical hardcourt Skill Rating.
Blue points represent matches before the injury, and orange points represent matches after his return. The dashed lines indicate the average service percentage and average opponent Skill Rating for each period.
The difference in Alcaraz's service performance is striking.
Before his injury, he won an average of 70.81% of his service points.
After returning, that figure dropped to 66.05%.
That represents a decline of approximately 4.76 percentage points.
In professional tennis, where matches are often decided by a handful of points, a difference of this magnitude can have major consequences.
But there is another important detail in the graph.
His opponents were not stronger after his return
Before the injury, Alcaraz's opponents had an average hardcourt Skill Rating of 1633.73.
After his return, that average was 1628.78.
In other words, the opponents he faced after his injury were, according to the Tennis AIQ model, slightly weaker on average.
A difference of approximately five Skill Rating points might sound insignificant, but it is not necessarily trivial.
Depending on the part of the rankings being examined, five rating points can represent approximately the difference between the world's number 15 and number 25, or between number 50 and number 70.
This makes the decline in Alcaraz's service performance particularly noteworthy.
His service-point percentage fell substantially, despite facing slightly weaker opposition on average. That does not prove that the injury caused the decline. Nor does an average opponent rating fully adjust for differences in individual opponents. But it does make one explanation less convincing: that his lower service percentage was simply the result of facing stronger players.
The data points toward a genuine change in his service effectiveness during the period examined.
What about his return game?
A decline on serve does not necessarily mean a player has become less effective across every aspect of his game. To explore that distinction, we also examined what happened when Alcaraz was receiving. Instead of looking at his own service-point percentage, we measured the percentage of service points won by his opponents.
The interpretation here is reversed: the fewer service points an opponent wins, the more effective Alcaraz generally is on return.
The second graph reveals a very different picture.
Before the injury, Alcaraz's opponents won an average of 58.04% of their service points.
After his return, that figure was 57.76%.
A difference of just 0.28 percentage points.
Compared with the substantial decline in his own service percentage, this change is negligible in the context of our sample.
His return statistics show no noticeable decline. If anything, the raw average moves slightly in Alcaraz's favor, although the difference is far too small to draw a meaningful conclusion from it. And because the opponents after his return were slightly weaker on average, we should not interpret this tiny improvement as evidence that his return game has become stronger.
The more defensible conclusion is that his return performance appears to have remained broadly stable, while his service performance has declined considerably.
That distinction is central to understanding the overall picture.
Why a 0.024-point decline matters more than you think
A drop from 70.81% to 66.05% in service points won is significant in itself. But the real scale of that decline becomes clearer when we translate it into the context of the Tennis AIQ model.
According to our model's SPW-score framework, the observed reduction in service effectiveness corresponds to a decline of approximately 0.024 points.
On its own, 0.024 might not sound like much. But at the highest levels of professional tennis, small differences in underlying performance can separate players who appear remarkably close in the rankings.
Before his injury, Alcaraz was clearly the second-strongest player in the Tennis AIQ Skill Ratings, sitting comfortably ahead of the rest of the field and just behind Jannik Sinner. If we apply a decline of 0.024 points within this model-based comparison, Alcaraz would fall from second to third, just behind Alexander Zverev.
At first glance, that might not seem particularly dramatic. After all, dropping from second to third in the world still leaves a player among the absolute elite.
But that is precisely where the numbers become interesting.
The exceptional level of Alcaraz hides the size of the decline
Consider what a difference of 0.024 points means elsewhere in the top 100.
According to the Tennis AIQ model, a performance gap of that magnitude is, on average, comparable to the difference between a player around the world's top 10 and someone ranked outside of the world's top 50!
That is an enormous difference in competitive level.
For most professional players, a decline of this size could represent a major shift in where they stand relative to the rest of the field.
For Alcaraz, however, it is partly absorbed by the extraordinary level at which he was already performing. Even after such a decline, his overall quality remains high enough to compete with the best players in the world.
His exceptional ability does not make the decline smaller. It makes the decline less visible in the rankings.
And that is an important distinction. A player can remain among the world's best while still experiencing a substantial deterioration in one part of his game.
Conclusion: still exceptional, but not unchanged
Carlos Alcaraz remains an exceptional tennis player. His results since returning from injury demonstrate that he is still capable of winning consistently at the highest level. But our analysis suggests that his serve has not yet returned to the level it reached before his injury.
Across 13 hardcourt matches in each analyzed period, his average service points won dropped from 70.81% to 66.05%. That happened despite his opponents having a slightly lower average hardcourt Skill Rating after his return. Meanwhile, his opponents' service-point percentages remained almost unchanged, suggesting that his return effectiveness has been considerably more stable.
And when we place the service decline in the context of the Tennis AIQ model, its significance becomes even clearer. A reduction equivalent to approximately 0.024 points on the model's SPW-score scale may only move Alcaraz from second to third in a hypothetical Skill Rating comparison. But elsewhere in the top 100, a difference of that magnitude can separate players by dozens of ranking positions.
That is the paradox of an extraordinary player: he can experience a major decline in one aspect of his game and still look almost unbeatable.
The real question now is not whether Alcaraz remains one of the best players in the world, because he clearly does.
The question is: What happens if his serve returns to its previous level?
Because if Alcaraz is already capable of winning this consistently with a substantially less effective serve, the potential upside of a full recovery could be inmense.