Attacking versus Defending On the Court

What is an attacking shot? Must an attacking shot be hit hard? What about a defensive shot? This essay will consider both the theory and the practice of attacking and defensive shots. And it will show that if you often lose 6-2 to an opponent then only a small amount of improvement might be enough to tip the scales the other way.

Tennis is a Game of Probabilities

Humans are not perfect. Anyone who has tried aiming for a small target by hitting balls fed from a ball machine will know that hitting identical balls will produce different outcomes. What is often not appreciated though is how sensitive the outcome of a tennis match is to small improvements.

Imagine a match played between two robots, where on average, out of every 20 points played, one robot wins just a single more point than the other robot. This is a very small difference in abilities. Mathematically, this translates to the superior robot having a probability of 55% of winning a point against the inferior robot. (I have used robots as a way of ignoring psychological factors. While the effects of psychological factors are relatively small, at a professional level where differences in abilities are so small to begin with, psychological factors can be crucial to determining the outcome of a match.)

Using the “Probability Calculator” found near the bottom of this page, we find that such a subtle difference in abilities translates into the superior robot winning a 5-set match 95.35% of the time. (The probability of winning a 3-set match is 91%.)

The graphs found on this page show that the set score is “most likely” to be 6-2 or 6-3 to the superior robot, so the next time you lose a match 6-2 or 6-3, believe that with only a small improvement you might be able to tip the scales the other way!

The In-Rally Effect of a Shot

While hitting a winner is a good (and satisfying) thing, no professional tries to hit a winner off every ball. Tennis is a game of probabilities, where subtle differences pay large dividends.

The aim of every ball is to increase the probability of eventually winning the point.

So if your opponent has hit a very good ball and you feel you are in trouble, you might think to yourself that you are down 30-70, giving yourself only 30% chance of winning the rally. Your aim with your return shot is to increase your odds. Even if you cannot immediately go back to 50-50, getting to 40-60 will then put 50-50 within reach on the subsequent shot.

So why not go for winners off every ball? If you can maintain a 55-45 advantage off each ball you hit, you will have a 62.31% chance of winning the game, an 81.5% chance of winning the set, and a 91% chance of winning a 3-set match. On the other hand, against a decent player, hitting a winner off a deep ball is difficult and carries with it a significant chance of failure, i.e., hitting the ball out. Studies have shown that even the very best players cannot control whether a ball narrowly falls in or narrowly falls out, meaning that winners hit very close to the line are rarely intentional but rather come from a shot aimed safely within the court that has drifted closer to the line than intended.

Attacking Options

If by an attacking ball we mean playing a shot that gives us the upper hand in the rally, then our shot needs to make it difficult for our opponent to hit a challenging ball for us. How can this be done?

First, our ability to hit an accurate ball relates to how well we are balanced, how much time we have to react, how fast the incoming ball is, the spin on the ball and the height of the ball at contact. So we can make it difficult for opponents in many different ways. The opponent’s balance can be upset by

The opponent’s neurones can be given a harder task by

Due to our physical structure, making contact with the ball outside of our comfort zone (roughly, between knee to shoulder height) decreases the margin for error because it is harder to “flatten out” the trajectory of the racquet about the contact point.

These observations lead to a variety of strategies for gaining the upper hand, including the following basic ones.

Each of these strategies carries a risk of hitting out, therefore, it is generally advised not to combine strategies: if you take the ball on the rise, do not also aim close to the lines or hit excessively hard, for example.

If you find yourself losing to someone but not knowing why, it is because subtle differences in the balls you are made to hit can increase the chances of making a mistake, and only very small changes in probability (such as dropping from winning 11 balls out of 20 to only 10 balls out of 20) can hugely affect the outcome of the match (such as dropping from a 91% chance of winning the 3-set match to only a 50% chance of winning). To emphasise, if your opponent takes the ball earlier than normal, you are unlikely to notice the subtle time difference, but over the course of the match, you will feel you are playing worse than normal.

If you are hitting hard but all your balls are coming back, remember that it is relatively easy to return a hard flat ball: the opponent can shorten her backswing yet still hit hard by using your pace, making a safe yet effective return. Hit hard and flat to the open court off a high short ball, but otherwise, try hitting with more top-spin.

Defensive Options

Just as an attacking ball need not be a fast ball, a defensive ball need not be a slow ball. Rather, a defensive ball is one where our aim is to return to an approximately 50-50 chance of winning the point. If we are off balance, or are facing a challenging ball, we cannot go for too much or we risk hitting out and immediately losing the point.

Reducing the risk of hitting out can be achieved in various ways.

Importantly, everyone is different, and you should learn what your preferred defensive shots are. For example, while flat balls inherently have a lower margin for error, nonetheless some people may find they are more accurate hitting flat than hitting with top-spin simply due to their biomechanical structure and past practice.

Placement of a defensive shot is crucial. Because speed, spin and/or time have been sacrificed for greater safety, it is quite likely that if the opponent has time to get into a comfortable position they can punish your ball. This is yet another example of where small differences can have large consequences: if the opponent can step into the ball you might be in trouble, yet hitting just a metre deeper, or a metre further to the side, might prevent this. Moreover, never forget that placement is relative to where the opponent currently is: hitting deep to the backhand is normally a good shot unless the opponent is already there!

Changes in depth can be very effective but they must be relative to where the opponent is. If an opponent is attacking, she might have moved to being on the baseline, looking to take the next ball early. Hitting a deep top-spin shot, not necessarily very hard, is very effective in this scenario because the opponent is forced to move backwards and thus cannot generate as much power. (A skilled opponent can still hit hard, but even a 10 km/h reduction in ball speed makes a large difference.)

Technical Considerations

Watching the slow-motion clips on YouTube of professional players hitting groundstrokes shows that the same player has many different ways of hitting her forehand and backhand. At the point of contact, you can look to see where her feet are, which way her hips are pointing, which way her shoulders are pointing, the angle of her wrist, and the contact point of the ball relative to the body. And as she hits, you can look to see which parts of the body are moving and which have momentarily become static.

While an upcoming article may consider such technical aspects in greater detail, here it is simply noted that while you should be able to hit every kind of shot from any reasonable contact point, each has advantages and disadvantages. And since tennis is a game of probabilities, it comes as no surprise that the top players instinctively know not just what type of shot to hit but also how technically to hit it in the best possible way for them at that particular moment: if they have time, and want to hit a heavy top-spin, they will probably choose a contact point further away from their body and step into the ball, while if they must return a very fast ball, they may instead use a more open stance and hit the ball more in line with their eyes, well out in front.

Next time you are on the court, experiment with how changing the contact point (even over a relatively small range of 10–20 cm) can change how hard you can hit the ball, how accurately you can hit the ball, and how much top-spin you can generate. And do not forget, this may change depending on the type of incoming ball. For example, generating pace off a slow ball is better done using a different technique than returning a fast incoming ball. Failing to recognise this may mean you “feel” you are not hitting the ball well when in fact you are just not using the best technique for the particular type of shot you want to hit.

The other side of the coin is recognising that sometimes it is necessary to play a ball using a non-optimal technique due to a funny bounce, or lack of time (or inherent laziness). In this situation, it is important to adjust the type of shot you hit. If you are forced to return a hard-hit ball at full stretch, you will lose accuracy, so do not go anywhere near the lines. If you are jammed, you are not going to be able to hit as heavy a ball as you may wish, so you may change to hit flatter, opting to take time away from the opponent. Of course, changing from heavy to flat generally means changing where you want your shot to land: a shorter top-spin that bounces above shoulder height is generally good whereas a shorter flat shot is generally bad, for example.

Happy hitting!

Jonathan Manton
13 Oct 2018


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