Service Ascendancy

podcasts Apr 11, 2020

 

Marc

Thanks again for joining us here on Crunching the Numbers for another episode, we are here with Marc Sophoulis and Shane Liyanage from Data Driven Sports Analytics. Shane thanks for joining us.

 

Shane

Hi guys, I must admit the three weeks working from home in self isolation' got me going a little bit crazy. Too many puzzles, I think. And I'm sure Marc's got a big job today to try and keep me in line and sticking to tennis.

 

Marc

It's a bit challenging. Obviously this time of time of the year where everyone's in isolation, but we're here to bring you as much tennis information as we possibly can, keep you up to date with what's happening in the tennis world. Obviously there's not much in terms of on court, but we can give you the latest in data and that's why Shane you're here to give us that next episode and our next topic, which is based around search ascendancy. So, do want to give the listeners a bit of a background as to, you know, what we're going to talk about today and the reason behind why we're doing it?

 

Shane 

Today I thought we'd look at the serve in particular. The influence of the server on the outcome of the point and throughout the podcast we'll give some tips to the server to try and maximize that influence and the returner to try to overcome it.

We're going to start with a little bit of theory and I can see Marc wince a little bit in the corner there, but I think it's really important to introduce these two calculations. They're interrelated terms that will form the basis of the analysis today, and really frame our discussion better. So the first is service ascendancy and what it tries to do is measure the point at which the server loses the advantage of that first strike. So, to work it out, we've charted each shot after the serve is hit by the server and the corresponding percentage of that point being won by the server. We also add in court positional data to give the calculations more precision. So it's considered a server loses the ascendancy on the shot in the rally where the server is no longer considered on the attack. And coincidentally, it actually lines up with the winning percentage of the point droppage of about 50% for the server.

Now the other term I'll introduce is serve impact. And alot of people tried to measure the impact of the serve, and the first person I've seen sort of doing the mathematical approach was Jeff Sackman and my calculations are slight variations of his, but basically what it does is it looks at the percentage of the service point, that can be credited or attributed to the serve. It looks at a number of things, so aces, unreturned, forced errors, that first shot. If it happens there, then that's probably a credit to the serve. But then, we'll look at subsequent shots, so plus one or plus two and on a sliding scale by looking at each shot it'll attribute something to the serve and something to the subsequent shot. And you'll end up with a serve impact score and a shot impact score, which totals 100%.

 

Marc

When you talk about... let's go to the first topic and talk about the losing the advantage side of things. So, can you be specific in terms of how do we lose advantage and when can we possibly lose advantage and what does that mean for me as a player or the coach coaching a player out there.

 

Shane

So Marc, I'll try and answer that with an example. If Ash Barty hits three shots after a serve is still winning 60% of the points at that point, and she’s in an attacking position then she's considered to still have her service ascendancy. But if on the fourth shot her winning percentage drops to about 50%, she's in a more defensive position then we consider her to have lost her service ascendancy.

So the service ascendancy really looks for the shot in the rally where a player loses the attacking momentum that comes from that serve and they're basically now in a neutral or defensive position and the rally becomes a battle between the server and the returner and the outcome is determined by some other subsequent shot, not the serve. Hopefully in this podcast we can provide, or provoke some thought really about what shots we can hit after the serve to try and keep that attacking momentum going, the service ascendancy. If you have a server and if you switch hats, what can you do as a returner to stop that attacking momentum? And you will notice this topic really ties in well with other topics we've talked about, about maximizing the impact of the rally in the first four shots.

 

Marc

Okay, so let's talk a little bit about players that probably don't rely as much on the serve as others, so you know you've got your one end of the spectrum, which might be Ivo Karlovic. You know if he doesn't have service ascendancy on the first two balls and finish the point, point's over for him. You know the rally will then go on and then he'll really struggle. But then you've got players that might just start the point with a serve, and then be able to use the groundstroke as their weapon, so do you look at both of those or do we average out those those sort of data statistics?

 

Shane

So in the analysis Marc we're looking at four years of shot data in both the ATP and WTA tours, so naturally you capture players with different strengths and weaknesses in that data set. And for our listeners I'll try and share some summarized statistics and the tables from the data set in the coming weeks on our social media channels. But I actually think the question you asked Marc is quite important in illustrating why looking at serve ascendancy and impact together is a good way of identifying clusters of players that rely on the serve in different ways. So you can look at that cluster, see the characteristics of that cluster, you can coach them a little bit differently to a player in another cluster. And conversely, if you're playing these players you can look at certain things about how you approach that match.

So the Karlovic's of the world, they'd have a high score in the serve impact, in fact nearly 75% of his first serve points are credited to that first shot, but he loses ascendancy, the attacking moment quicker than the average player. Whereas if you look at a player like Stefano Tsitsipas, doesn't have such a high serve impact score. But what he does do when the first ball comes into play, is he's able to continue whatever advantages he's got, so the ascendancy he keeps going with the second, third, fourth shots. He keeps on going.

 

Marc

I think that's a really good point, though the biggest concern for me with the players I've worked with a lot of the time is that they'll serve the ball and that first ball that comes in, they don't take that initial strike. And if you don't take that initial strike you basically almost lose the ascendancy from that first ball and I think what we as coaches need to push (obviously if you're a parent out there helping a child or if you're a player out there on the court) is, it's not just what you do on the serve, it's that first ball on that first opportunity to strike. We as players need to take that, because if we don't take that, then the opponent will take it and push us back and then we lose ascendancy within two or three shots. I think that becomes critical to us winning or losing that point.

 

Shane

Yeah. So let's look at some high level stats with serve ascendancy, and then we can look at specific players later. So, first the first serve on the men's side, by the fourth shot, the men lose the service ascendancy and for the women they lose it by the third shot. And on the second serve, the men lose it by the third shot and women lose it on the second shot. Marc what are your tips for a server to try and maintain that ascendancy and conversely, what do your tips for returner to to try and counter the server's ascendancy?

 

Marc

Look, I'm always a big believer that we've got to play to our strengths, so especially on the big moments where it's critical, critical scoring systems like 30-30, deuce, a break point. I think we've got to look to serve to our favourite serve, regardless of whether you feel like the opponent will read that ball. And once you serve to your favourite serve, I think it's important for them to follow up with your best shot. Now, if you're if you're out there playing and you're just, you're comfortable with playing any shot on the court, okay that's fine, but I feel like the best players in the world, male and female, all serve and utilise the forehand to generate as much ascendancy early in the point as they possibly can.

On the flip side, the returner has to neutralise that. So, if you're out there returning, it could be your court position that might help you neutralise that, it could be the ability to step into the court and really drive the returns as opposed to just sort of put the ball back. It might be the ability to play through the middle of the court. And a lot of the players these days are playing returns through the middle of the court to try and neutralise the rally and not give too much angle on that first ball.

And I feel like over time, this ploy has taken more of a front seat in that players are now, male and female, returning more through the centre to try and not allow the opponent to get that first strike angle and have to go first strike through the court. And if a player has to go first strike through the baseline, that then keeps me inside the court a little longer. And it doesn't make me get on the run, so then if I'm not on the run I can actually have a better strike on my next shot. So, it becomes, for me it's the challenge of are you winning the serve first strike or the return first strike? And if you can do either one of those you become, obviously in control the point. And if you're in control of the point you probably win that point, more often than not, so you know obviously it's a it's a really important part of the game now. I think we talked about the first four shots in previous episodes, where it's important to win that zero to four point ratio. If you're not winning that you're going to lose a majority of your matches. 

 

Shane

To go back to that second measure, the serve impact, the calculated data on the tour shows that the serve has much more of an impact on the grass, with about 70% of first serve outcomes on the men's side (ATP) credited to that first shot, the serve, and nearly 60% on the WTA. The other end of the spectrum. Were talking about clay, which would be 5% of the points, the first serve points, credited to the very first shot, the serve and 35% on the WTA tour. So I'm gonna ask you a two-parter Marc. What are your tips for serving on grass? And because you get some assistance from the surface, and more point outcomes are decided by serve on grass, should you be serving within yourself or going for a little bit more?

 

Marc

Look I think, you know, there's a huge part played by the environment we play in. There's no doubt that all the surfaces will throw up a different element of what we think about when we play and I think as a player, if we're not thinking about those elements then we're in a bit of trouble. I guess the one thing that I hear a lot of, and we talk about elements that affect us, it's not just the court surface, but it could be the wind. And you hear players out there and, you know if you're out there and you're a coach or you're a parent and you're listening to this, you'd be hearing it constantly from your players, your kids saying, oh it was windy I couldn't serve.

You know, I think it's a total crock because at the end of the day, you know the elements help us to achieve things that we need to achieve. So when we do play on grass as you said Shane, utilising the slice serve with a ball that just takes off is a real critical component. The more you maybe kick serve or the more you hit a flat serve, the ball might sit right in the zone and allow the opponent to have a better strike on the return. So you have to use the elements to the best of your ability.

Now, those elements might mean that you might...if you feel like the grass slice serve is the best serve, but the opponent has a weaker backhand return, you can still slice it into the backhand. So therefore the ball actually takes off on the grass as well and jams him up. So you can still use that element, but you can then tailor it to the opponent as well and you can go; well they struggle in this situation, let's utilise this serve. And you might think of obviously grass has the slice serve that we need to utilise more. Clay, obviously with clay being a slower kind of environment, you know, you try and nail the serve, but the opponent probably has a deeper court position. So you really have to think about what first shot do you really want to get back? You know you see a lot of players on the clay will really hit a heavy kicks serve to force the opponent right back on the backhand wing so that can't generate force, and then take the time on the forehand to really load up. So I think the elements form me Shane are really important because, if we're only looking at data, if we're only looking at the players' strengths and weaknesses and not focusing in on what the elements are giving us also then we're taking away a big part of what can and can't be done on serve. So there's a lot of things that need to be taken into account when you stand up the line for you to serve and elements is definitely one of them.

 

Shane

Yeah. But Marc you touched on clay before. One of the common misconceptions that I hear is the serve is not important on clay. The numbers show that the service shot is still credited to about 55% of point outcomes on the clay on the ATP and 35% on the WTA, so these are still some substantial numbers. I might ask you, what different kinds of serve should we be hitting on the clay to get something from the surface, and then also what serves work well to set up the point so the player can maintain that ascendancy to keep it going longer?

 

Marc

Good question. I wanted to come back to you for that last question because we talked about the serve not being as important, and people also say volleys are not important on clay. But yet the volley ratio, winning ratio at the net is more significant probably on clay than most other surfaces. So I feel like we put surfaces into a pigeonhole and say we can or can't do something on the surface. It used to be you can't stay back on grass. And now you look at Wimbledon and all the wear marks are at the back of the baseline. Everybody's staying back and everybody used to say that you can't come to the net on clay, and all of a sudden the winning ratio on clay becomes becomes larger now. So I feel like we do this a lot and I think now when we talk about serve on the clay, obviously depending on who you are, depends on what serve you need to hit.

So if you want time on your first strike you're probably going to kick serve. And you want to get the ball up and jump it up and push them back, or if you've got a big server and you can utilise that you might nail the serve and obviously get them stretching and then get your first strike through that. You might try and look at the body serve. You might try and look at, you know, trying to slice them and if they're standing so far back and slice it short, so therefore to move forward and you create more angle. It really depends on who you are and what your better serves are. You're not going to say to Ivo Karlovic, take away your 230km bomb and just roll the first serve in. So I think it's playing to each other's strengths, or play to your strengths is the most important part about any kind of serving, and not taking that away just dependent on surface.

 

Shane

I hear you, so understand the subtleties of the surface but stick to your strengths. I'm going to read out a few players and I want to hear the first thing that comes to your head when I say it. Ivo Karlovic, John Isner, Reilly Opelka, Denny de Schepper, Marius Copil.

 

Marc

They're tall, they've got massive serves. And probably not as strong off the back of the court.

 

Shane

Yeah, you're spot on. These are four big guys. Four of them are pushing six-nine, six-ten or above. And they've all served over 240 kilometres at some stage. But you alluded to the other point that they're not as strong from the back of the court. So there's a couple of reasons why I read that list out. The first is, if you plot serve impact and serve ascendancy for the tour, you will notice that these players fall into a cluster that's considerably distinguishable from the rest of the tour. And the characteristics of this cluster include: Their service points, in particular, first serve are highly impacted by the first shot, the serve, but they lose serve ascendancy within three shots of their serve. So if you're a returner, and you can withstand two or more shots from them, you're most probably at a neutral position now and every shot after that turns into your advantage. Much easier said than done.

The other key characteristics of this group: They don't win any rallies over five shots. They start to lose more than they win, but it's important to contrast this with someone like Nick Kyrgios, who most tennis observers and commentators would agree has arguably the top three or four best serves in the game at the moment, but he actually falls outside this cluster of players because he can maintain his serve ascendancy longer with his subsequent shots. So his ball handling, he can do a lot of damage with that to continue the ascendancy for a lot longer. Now I am going somewhere with this, because the second reason I mentioned this group of players, was I worked on a team last year with a player and a coach, and they ended up playing players in this cluster - four of them in fact. And generally we go into a lot of the matches with a mantra, primarily focusing on the strength and doing what what we can to maximise that, but we deviate a little bit from the mantra, because we identified how disproportionately players in this cluster relied on this serve in comparison to other parts of the game. And I'll mention something a bit later, from a practical point of view what the coach and the player did to prepare. But before I do that Marc, if you have ... I might ask you a question, if you have a player under your wing that has an incredible serve, but is weaker in other parts of their game, how much time you put into improving his weakness compared to developing the strength more?

 

Marc

It's a great question you asked. You know, I these debates with people all the time - do you work on the strengths of the athlete, or do you work on weaknesses of the athlete and try and get them to a level? Now if you work on things that are not breaking someone's game and you put so much emphasis on to that, what happens to the strengths of the player? Does it continually get better or just stay the same? And I'm glad you brought up that example and I can guarantee you guys, the listeners, this is not a setup, but we had an opportunity for the player I was coaching to practice with Ivo Karlovic at the Australian Open a few years ago, and his whole practice was based around just serves. Literally. There was no rally stuff. It was just serve and it was point play. And the biggest problem I find is... every time he's in a tournament, and I feel for this guy, and you can probably give me the data, but he's been top 50 for probably 10 years or top 100 for 10 years whatever it might be.

 

Shane

Yeah, 17 times in a row in the top hundred.

 

Marc

Now, nobody in any tournament signs up to practice with Ivo Karlovic. Nobody. He cannot find a practice partner. Why? Because you can't get anything out of a session with him because he serves aces and unreturnables. So, I think, and we'll go back to your question, is that you need to practice your strengths a lot more than you need to practice your weak areas of your game. And make your strengths that strong that they can't be broken and Ivo when we practiced with him, oh my goodness, it was incredible. My player was having a break I stepped on the court to do some returned to serve, because Ivo wanted to practice more serves, and the ball was bouncing above my head and you know I'm five foot 11. The ball was bouncing above my head on the first serve. And you know you feel like you just cannot break him. And that's how he's stayed at the top of the game for so long, he gets every set to a tiebreak. He may not be able to return serve as well, but you know what he's always a chance  when it gets to a breaker and so, you know, these are the kind of things that I think are really important to weigh up when you're a coach out there or a player and you're thinking about your game is - how much time do you spend on your strengths, and how much time should you spend on the weak areas of your game. It's a really important thing to weigh up because you don't want to get that wrong.

 

Shane

Just to complete the story I raised earlier. The team I worked with didn't want to stray too much from the players strength, but did want to try a few things to try and minimise the impact of the strength of the other players. So some of the practical things that we did when versing players in this cluster were to practice like reality. So the coach was actually on the service line replicating the speed, trajectory, height, angle on the serve and the player continually faced returns before the match from those positions.

One of the other tactics that we'd come up with was to continually adjust the return positions, mainly on the ad side to throw the rhythm of these players off a little bit. So in practice that's what we did. I remember sitting on the sidelines and the player continually adjusted from a shorter return position to a deeper one, but did that in practice, and then was able to take that into the match and they felt more comfortable in the match doing that. The other part which we also used data for. We identified that this cluster of players, generally play very fast in between points, so usually in less than 20 seconds, they're back on the line again. They played faster though if they win the previous point. So, our guy, the data said that he actually likes to have about 20 to 25% on return games, and he returns better. So we wanted to maximise that so within the allowable limits of the game we looked at ways to slow the opponent down, so put the hand up, get the towel. All of those things helped in reducing the rhythm of the opponent and they served a bit... in all those matches we actually ended up fortunately winning all of them. And the first serve percentage was actually a bit lower than their general average, so I know that's an example. One example and I know all players are difference so you can't necessarily take that kind of approach, but a general question for you Marc - when you identify an area that's such a liability for the opponent. How do you find the balance between exploiting the weakness and not deviating too much from your player's strength?

 

Marc

Alright, this is a podcast in itself my friend, this is gonna be...this could be a long winded answer, but I guess the short answer to it is whenever I develop a game plan, it's based around 80% what you can control and 20% the opponent. You know, you don't want to be changing your game and what you've practised for so long and your style of game. You don't want to change that just because you playing against someone who has a great forehand, or a serve volleyer. You know if you're Rafael Nadal, your strength is your forehand. You don't want to be playing... just because you're playing Roger Federer and he wants to come to the net, you don't want to try and come to the net before him. You know, it's really important to make sure that you play to your strengths more than anything and stick to 80% of what you can control. So I reckon you've just hit the nail on the head with a new podcast for us coming up, I reckon we can you talk about game planning and different ways of beating opponents because I think that is a really big element, but is there anything, one last thing from you Shane?

 

Shane

Thanks Marc. For the 80/20 analogy you mentioned where 80% of the focus is on the strength is a great point to end on in my opinion, with the data work I've done with players we certainly focus on using the data on the strengths of our players to address the weaknesses of the opponents, as opposed to letting the tail wag the dog, where you look at the opponent's weakness and then trying to reinvent the player to match that. So parents and coaches out there. My recommendation is try and get some video of your players or squad. Tag those matches and then use measures like serve ascendancy and serve impact to segment cluster your players. Similar to how most businesses would segment their customers and taylor their approach to dealing and helping them - do that with your tennis athletes and don't lose sight of that 80/20 approach and focusing 80% on the strengths of that cluster and 20% on the weaknesses, but a tailored approach is really recommended. Before we end on today, I'd like to throw it back to Marc and really get some takeaways for our listeners to try and maximise and keep the serve ascendancy going.

 

Marc

Yeh I guess I've got four points here that I that I wrote down as you were talking I think the first one was - serve to set up your plus one. Don't just serve. I think that's important. I think, I'm not sure the percentage of points that will finish in an ace for most players, but it's not going to be a huge element for a lot of players, so make sure you serve to setup the plus one. It's the person who gets the first strike that will get ascendancy for the rest of the point. So if you serve and get a first strike in, which is a really solid first strike, you're probably getting ascendancy, and the returner obviously on the flip side needs to be able to take away that ascendancy from the server. So return to get that first strike and usually through the middle ball is the most important.

The third point for me was serve to your strengths. Critical moments is where people start to... they know I'm serving to the backhand and I'd better change it. You know, for me it's not about that it's like, well, if that is working for you and that is your favourite serve continue that in the big moments. I feel like we change things only for the sake of changing it, because we think the opponent knows where we're going. It's irrelevant. If you serve well enough, Nadal plays a forehand every ball he can. Everybody knows he's going to play it, everyone knows where he's gonna play, but he plays it that well you can't get it back. So I feel like we've got to play to our strengths more often.

And the last point was use the elements. So, whether it be the court, whether it be the wind, whether it be the sun, whether it be... whatever it is that you can utilise use it because you need to be able to highlight those things and use it to your advantage. It might be a 10% difference, but that 10% could be the difference in you winning or losing the match. So they're my four takeaway points for today's podcast Shane and I do appreciate your time as always. The amount of research you do is incredible. You can find Shane at Data Driven Sports Analytics, all over social media, Shane Liyanage as well. Follow him he's got so many social media things happening, so many different data that you put up, weekly, daily. So thank you so much again for your time and what you do for this podcast.

 

Shane

Thanks everyone for listening. I hope you've had a great week and we'll see you next week.

 

Marc

Thanks so much for joining us once again here on Crunching the Numbers. You're again with Marc Sophoulis and Shane Liyanage. Follow us on The Tennis Menu and Data Driven Sports Analytics for more around the tennis and we'll keep you up to date as much as we possibly can here on Crunching the Numbers. Thanks again and we'll see you next week.

 

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