Kei Nishikori. Hawk-Eye Analysis Part 2

Earlier this Japan’s National Broadcaster (NHK) contacted me to provide analytical support for a documentary they were preparing on Kei Nishikori. Part II of the documentary went to air in Japan recently and I thought I would share a few screenshots with you of the final animations and analysis.

Kei Nishikori Documentary

The analysis focused on a number of key matches Kei had played over the last 12 months including:

  • Wawrinka at the US Open, and Aus Open.
  • Murray at Madrid and the World Tour Finals
  • Djokovic at the US Open and Rome.

Below is a brief explanation and some examples of the analysis:

Nishikori v Wawrinka (US Open, and Aus Open)

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Wawrinka made some adjustments to his game after loosing to Kei at the US Open. The above graphic shows you the balls Wawrinka directed to the deuce side of the court at the US Open.

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We saw from the footage that Wawrinka was targeting Nishikori’s forehand out wide and so we ran some numbers on it. We created a simple density surface of the shot location for Wawrinka at the US Open (pictured above) and at the Australian Open.

Nishikori Wawrinka

At the US Open Nishikori was given too much space and angle on his backhand and really made Wawrinka pay hitting a number of winners of this side. At the Australian Open Wawrinka made an adjustment and targeted Nishikori’s forehand, pulling him off the court with a number of short angled forehands. Below is footage of where Nishikori ended up on a number of important points which gave Wawrinka an easy shot into the open court.

Nishikori Australian Open

Nishikori v Murray at Madrid and the World Tour Finals

Nishikori beat Andy Murray at the World Tour Finals in 2014 but Murray was able to turn the result around in Madrid during the clay court season earlier this year. One of the reasons why was because of his serving. In particular his accuracy and depth at important points. Murray also served far fewer second serves at important points in Madrid than he did at the World Tour Finals. If you’re serving short 2nd serves to Nishikori at important points than Nishikori is going to be all over the return and you’ll be playing catch up all point!

Murray Serve Position Hawk-Eye

Above is Andy Murray’s serve pattern at the World Tour Finals (where he lost).

Murray at Important Points

In the purple are Murray’s serve locations at important points at the World Tour Finals. In the green are Murray’s serve locations at important points in Madrid. Check out the six short serves that Murray dropped at the World Tour Finals (these were all second serves). These provided easy pickings for Nishikori. By comparison, Murray only served 1 second serve in Madrid, and his 1st serves were much closer to the lines in Madrid.

Murray was also getting some heavy rip on his serves in Madrid which forced Nishikori to regularly hit the serve return above his shoulder making it hard for him to get any real pop on the return. Murray’s serve in Madrid made it very difficult for Kei to gain the ascendency in the rallies. Players are looking to expose Nishikori’s height particularly on the serve return where he can be very damaging. Both Murray and Djokovic (in Rome) went after this as the neat little graphic below illustrates. It shows a comparison of the average height Nishikori’s was playing his returns against Djokovic at the US Open (blue) and Rome (yellow).

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We also identified that the three opponents (Wawrinka, Murray and Djokovic) played much straighter through the court against Nishikori after their losses at the US Open and World Tour Finals. The two graphics below highlight what this means for Kei. His opponents took away the angle from him on his groundstrokes and didn’t allow him to pull the trigger, particularly from the backhand corner which is one of his favourite shots.

Nishikori Angle of shot

Screen Shot 2015-07-12 at 3.44.23 pmWell there’s just a few examples of the visualisations and analysis we run for the show. Millions of data points, and hundred of hours of data mining and statistics were run in search for answers to so many questions. Unfortunately I can’t share any of the analysis in depth with you but hopefully this gives you a little taste of the some of the analysis that was completed. It was a real privilege to work with the talented team at NHK, they have an extraordinary high work ethic and seek perfection in their work. We are all extremely proud of the result.

Images copyright NHK. Do not share the contents of this web page without permission from Gamesetmap or NHK. 

Murray’s Act of Tennis Espionage

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Andy Murray training with Nishikori in Miami earlier this year. Source: NHK.

In a recent documentary on NHK it was revealed that a new level of espionage was creeping into men’s professional tennis. It was reported that Andy Murray approached Hawk-Eye to track his practice session with Kei Nishikori at Miami earlier this year. It was also revealed that Murray was now a regular customer of Hawk-Eye and is using the data to seek new insights into his game, and his opponents.

In recent years there have been a number of high profile spying events in sport that have made headlines. In 2007 the New England Patriots were caught filming the New York Jets defensive coaches’ signals during a game. In 2014 the French National Football (soccer) team sighted a drone over one if its practice sessions prior to the 2014 world cup and in the same year Australian Rules Football club Port Power ejected an opposing spy from one of their training sessions.

Spying on rival players in tennis is not new. Tennis coaches have long sat courtside at practice sessions to try and catch a glimpse of their next opponent or an up and coming player making headlines in the junior ranks. Coaches and players regularly use video to scout opponents technique, tactics and fitness. But Murray’s request for Hawk-Eye to secretly track a training session is perhaps a whole new level of spying that we have not seen in tennis before. Did Murray crossed the line? Are there even rules in place to prevent this?

Players can request match data from Hawk-Eye at any time. Few do, but the option is available for them and this is within the rules. What’s interesting is that this is the first time we have heard players requesting that the Hawk-Eye system be turned on to secretly track the ball and player movement in a training session. From what we understand Nishikori had no knowledge about Murray’s request.

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Inside the Hawk-Eye bunker in Miami during Murray’s training session with Nishikori.

The richness of the Hawk-Eye dataset cannot be underplayed, evidence of this was on display during the NHK documentary. One of the huge advantages to players is that when they make a request for the data they are supplied with both their data and their opponents data. So not only can the player answer questions about their own game but they get valuable insights into their opponents too. It does however raise the question about what benefit a single training session would provide to Murray. From my experience a single match, and in this case a single training session only provides a limited insight into a players patterns and tendencies. Studying trends and patterns over time is where the real value lies.


The output from Hawk-Eye during the Murray Nishikori training session.

Murray is no stranger to technology. He recently joined the board of Seedrs Advisory where he gives business advice in the areas of health, sport and wearable technology. His growing interest in UK tech starts ups shows he has a genuine interest in this area, and he seems keen to use the latest technology to his advantage on and off the court.

Other sports like the NBA, EPL and NHL are caught up in an analytics storm at the moment. Tennis has traditionally been left in the dark ages with respect to analytics but perhaps Murray’s actions are confirmation that the game is changing. Tennis players and coaches are becoming more intrigued by analytics, and the data that is being collected on them. Murray is now a regular user of Hawk-Eye data, but it seems he is keen to take advantage of the system one step further. Perhaps Murray was simply being curious? Or perhaps he and Amélie Mauresmo had genuinely planned to gain insights from the training data. Players are starting to ask the right questions, and some of them are clearly pushing forward with their own independent analytics and detective work. I say fair play to Andy Murray for pushing the boundaries, and seeking an edge wherever he can. Tennis may be on the edge of a new frontier in analytics after-all.

The Symmetry of The Tennis Serve

Late last night I was running some analysis on serving, and serve return hit points and I stumbled across this 3D view of the data which made me stop and marvel at how unique the symmetry of a tennis serve is. The image below visualizes over 350 serves. The view of the image is taken from side on to the court.

Tennis Serve Hawk-Eye

  • The blue dots represent the serve trajectories.
  • The yellow dots are the location of serve bounces.
  • The red lines are the trajectories of the ball bounces.

This image was created using Hawk-Eye data from an ATP men’s match. Tennis is a unique game in many ways, and the data driving the game is more beautiful than ever. Unfortunately I can’t share any of the results from the analysis but I hope you appreciate the symmetry in this rare image like I did.

Official WTA finals app likely to open up a can of worms

Today the Women’s Tennis Association (WTA) and SAP announced the launch of the official WTA Finals mobile app just in time for the BNP Paribas WTA Finals in Singapore – press release.

WTA Official AppThe app has been in progress for much of 2015 so I was happy to finally see SAP and WTA deliver on their promise of “taking the fan experience to the next level.”

The app has all the usual features of a tennis app; live scores, news and videos, schedules, draws etc. But what makes this app “groundbreaking” is a feature called Virtual Replay where users can watch an animated point-by-point replay of the match unfolding right before their very eyes. It’s kind of cool to watch the ball trajectory animate over the net between the players (for what it’s worth). Unfortunately it’s not clear which player is playing at which end as the animation runs through. You will need to read the commentary of the point from below the animation to figure that out.

WTA Virtual Replay

The default view of the animation is a normal camera view (from one end of the court) but users have the ability to change the view to 3 other camera angles which is a nice touch.


Users can then choose which point they want to watch from the point-by-point breakdown, which is a neatly organized commentary of each point from the match showing the point score, and key actions made by each player.

The app also includes additional visualisations like Serve Direction (below).


Return Strike Points


Shot Placement

WTA Shot Placement

Rally Hit Point


All of the visualizations allow you to switch between players, and you can change the Set you want to view at any time. It all makes for a very impressive mobile application, and is certainly light years ahead of any other tennis app I have seen. It is also no mean feat to package all of this content up in a very usable, and engaging mobile app that fans are sure to love and embrace.

So how useful is all of this? Well, to be honest we’ve kind of seen it all before. Hawk-Eye through their various relationships with TV Broadcasters like ESPN and the BBC have been publishing these types of visualizations for a number of years. Admittedly we have not had access to this level of information post match and in the palm of our hand before, so this is new ground definitely. But we are not really seeing anything new here.

The visualizations in the app unfortunately lack some valuable context in order to make them really useful for players, coaches and the fans. For example they are simply static representations of the data. You can’t query them (by touch), or filter them, or overlay one player’s points on another in order to perform any additional analysis. There is no significance attached to the data, like winners, unforced errors, big point plays etc. There is no way of knowing whether the patterns we see are expected, or a cause for alarm given the sate of the match, or past performances against this player. Perhaps we’ll see this kind of contextual information added in future releases. SAP and the WTA claim they have worked closely with the players to develop the app to their needs. However my feeling is most astute coaches and players will see these visualizations as nothing more than eye candy (for now).

As a tennis fan, and analyst of the game, the application naturally left me wanting more, and I suspect coaches and players will feel the same. What the WTA has effectively done is open up a big can of worms. The visualizations in the app leave so many questions unanswered, which is not untypical of a all-in-one app like this. But it does provide a wonderful insight into the potential of these kinds of visualizations. In order for players to really benefit from the true potential of this rich dataset from Hawk-Eye they are likely to still undertake independent analysis which dives much deeper in geographic patterns and tendencies than what we see here.

Hats off to the WTA for leading the way with this new-age tennis app. It has raised the bar and expectation going forward, and it definitely takes the mobile fan experience to a new level. I look forward to hearing what the players and coaches really think. My understanding is they will be given a more comprehensive app for on-court coaching, which may pack a few more tricks than what we see here. That may or may not be a good thing given visualisations like these tend to take time to digest, assess, and decide what action to take. This will be a new challenge for coaches, particularly in the heat of the battle. My sense is this kind of information will be primarily used post-match when emotions and the tension from a match have passed. It will also be interesting to see how the ATP respond over the coming months/years. Perhaps they too will partner with SAP to deliver a similar app for the mens tour if this takes off.

The WTA application was tested on an iPhone 6.

Presenting a Diorama of Player Movement in Sport

Earlier today Sports Performance and Tech magazine published my article on visualizing Hawk-Eye player tracking data. The article explores the value of 3D and Space Time Cubes when displaying spatio-temporal data.

To create the Diorama I used 3D optical tracking data from an official Hawk-Eye tennis match played between Roger Federer and Paul-Henri Mathieu at the Swiss Indoors in Basel, 2012.

Sports Performance and Tech Magazine

A Diorama of Player Movement in Sport

A Diorama of Player Movement in Sport

The full article can be read here.

A Diorama of Player Movement in Sport

To explore the 3D Diorama in more detail please visit the app here.

*** The app is best viewed on a computer or laptop using Google Chrome ***

Unlocking Hawk-Eye data: What it means for tennis, the ATP, WTA and ITF.

Since 2005 the governing bodies of tennis (ATP, WTA and ITF) have been collecting data using Hawk-Eye for many top-level tournaments and the Grand Slams. So what have the governing bodies been doing with this data? Where is it stored? Who owns it? Who has access to it?

Hawk-Eye WimbledonHawk-Eye was introduced to tennis in 2005. Since then, the governing bodies of tennis have been collecting valuable data about match play. Image: Hawk-Eye Innovations.

Some background

Early in 2012 I set out to start mapping tennis matches. As a Cartographer, and tennis player this kind of made sense and excited me! Tennis is a spatial game, meaning that the location of the ball and the players are linked spatially to the court. So at any time during a match we can plot where and when a stroke, or player is. The concept of mapping sports matches is not new. It has been around for some time now and is commonly referred to as Sports Analytics or Spatial Analytics. Many sports like Football (Soccer), Basketball and Baseball have been using analytics for years to explore potential unknown patterns about the game, their players and their opponent’s tactics. We have all seen Moneyball right?

To kick off my research into maps about tennis I manually plotted the ball location and player movement from the London Olympics Men’s tennis final using video footage and a 3D visualization application. The results of the research can be read here. This method of data capture was perfect at the time because it allowed me to captured the tags I needed to run my analysis on. As a result of the research I have had tennis players, coaches and other tech companies contact me wanting help analyzing their players patterns, strengths and weaknesses using similar methods as outlined in my research. Sure, I replied with over-the-top enthusiasm. But, we have to manually capture the data first, and that tends to be time-consuming and a tad laborious. So the client says, “Can’t we use Hawk-Eye?” That’s a great question I tell them, but it’s not that easy…

The search begins for Hawk-Eye data

So how would one go about getting access to this infamous Hawk-Eye data that everyone apparently everyone knows about (like its their brother), has seen on TV, but no one knows where it is or who to contact to get access to it? Go direct to Hawk-Eye?

To cut a long story short: Hawk-Eye state that they don’t own the data they capture. The tournaments do. Or do they? After spending the last 6 month trying to track down the right people in the right place at the right time I receive this response recently from Tennis Properties, the management group who runs the ATP. “Tennis Properties own all of the Hawk-Eye data from the Masters 1000 tournaments. We don’t license this data to 3rd parties”. Well at least that clears up who owns the data. But of course that wasn’t the response I had hoped for!

I then turned to Tennis Australia. I figured they might care to share some Hawk-Eye data with another Aussie. This was their response “The Hawk-Eye data is owned by our commercial/IT teams…. but it is not for use for commercial or external endeavors”. So they own their Hawk-Eye data, not Tennis Properties. Confused yet?

So my search started targeting the ATP 500 series tournaments. Tennis Properties had told me that each of these 500 series tournaments has their own agreements in place with Hawk-Eye and that the ATP does not control the data captured at these tournaments. Sounds promising right? Well it was. The team running the Swiss Indoors tournament in Basel granted me permission to all of their match data for their 2012 tournament. I was ecstatic. Finally I would be able to grow my research, and potentially help some of the pending requests from other interested parties. However, they didn’t have the Hawk-Eye data in-house (sigh). I was then directed to Hawk-Eye themselves to retrieve the data….

Swiss Indoors BaselThe Swiss Indoors at Basel granted me access to their Hawk-Eye data from their 2012 tournament.  Image: Swiss Indoors.

A further six long months has passed and I am yet to see any sight of the data from Hawk-Eye. Apparently they are too busy to attend to the request of the Swiss Indoors to release the data (grrrggh!).

Why is Hawk-Eye data so protected?

The answer is simple. The data that Hawk-Eye collects is very powerful. It collects the location of the ball and player, the spin of the ball, speed and flight of the ball (just to name a few). If the data lands in the hands of someone who can pull it apart and reveal patterns about players and opponents (that may not have been seen before) then it becomes a potential sticking point for the ATP, WTA or ITF. Or does it? Let’s take a look at this from another point of view.

Bob Kramer, the former tournament director of the Farmer’s Classic* in Los Angeles, said the technology ran at his tournament cost about $60,000-$70,000 for one court, with much of that cost going to installing the infrastructure. Now if I was a tournament director and I was spending that kind of money on new technology then I would be keen to explore ways I can recoup some of those costs. One of those ways may be selling/licensing the Hawk-Data back to its players, the media and fans. Oh but wait, the tournaments can’t do this because the ATP, WTA and ITF control the data. Or do they?

So who really owns Hawk-Eye data?

The tournaments seem to be funding the implementation of the technology (the richer tournaments like Indian Wells have more Hawk-Eye courts than say Miami) so is it their data to share and/or commercialize? Or is the data in fact the player’s data? They are the ones putting on the show; the data is about them, not the tournament. What if Roger Federer or Serena Williams wanted access to the Hawk-Eye data? How quickly would the ATP, the tournaments and Hawk-Eye react to their request? Are they permitted to even access the data?

Tennis unlike Basketball, Baseball and Football (Soccer) is an individual sport, played mostly on neutral territory (with the exception of Davis Cup). In team sports, it is the teams who are collecting the data at their home games, not the governing bodies of each sport. So where does this leave the players? Does Novak Djokovic have to bring his own data capture equipment on court to trace him movements and map his shots? Let’s hope not!

Novak DjokovicWorld number 1, Novak Djokovic may have to bring his own data capture equipment to matches to record his shot patterns and movements! Image: Reuters

What’s in it for the ATP, WTA and ITF to unlock (open) Hawk-Eye data?

Open data initiatives have been actively gaining momentum (outside of sport) as governments and private industry see the benefit of making their data freely available. Late last year however, the Manchester City Football Club (MCFC) opened up some of its match data so it could crowd source new ways of visualizing the data and encourage innovative ways of making use of it (read the Forbes article about the MCFC program here). They were essentially tapping into the crowd’s knowledge and passion for the game to better understand their players and opposing teams. If the governing bodies of tennis were to do this it would open up a unique opportunity to engage with the fans and media like never before. Tim Davies whom is an open data advocate calls this making use of “social infrastructure” that surrounds sports.  Opening up the vast of amounts of tennis match data available at a relatively low cost (or for free), would lead to third party innovation, where the next generation of tennis fans could design innovative products, which may result in a new wave of interest in tennis analytics and spawn many new products in tennis. Imagine what IBM could do with data, or anyone else that has an interest in commenting and reporting on the game? Imagine the maps and graphics that the tournaments could supply to the pressroom at the end of the day to help report on the days play!

Opening data can be scary (but it’s time to be brave!)

Opening up your data to the whole world can seem scary at first. There is no doubt the ATP, WTA and ITF will have reservations about doing so. But think of the increased two-way interaction, between the innovators and the data suppliers. Perhaps Hawk-Eye data can be extended way beyond what it is currently being used for? Perhaps there is a revenue stream back to the tournaments that may offset their cost of installing the technology. The data may even be turned into physical products, like artwork for Nike’s next Rafael Nadal t-shirt! Who knows? History has shown that opening up data is not in fact scary, it is incredibly exciting and the possibilities appear endless.

Andy Murray Tennis ArtAndy Murray poses in front of ‘tennis art’ at the O2 Arena in London last year. Andy created the unique portrait of himself that was auctioned off for charity late last year.

Natural Evolution for Tennis

Unlocking Hawk-Eye data is a natural evolution for tennis. As pressure builds on the ATP, WTA and ITF to-be-seen-to-be-keeping up with other sports, perhaps the locks will come off the data. At present, only the TV broadcasters and national tennis associations appear to have a key to the data. Sadly, there is a very valuable stockpile of data gathering dust on some internal server at Hawk-Eye with no use for it all! Of course you might get lucky and be granted access to a portion of that data but fail to ever see it! It will only take one of the ‘next gen’ of players, like a Sloan Stevens or Milos Raonic who understand what modern analytics can do for their game, or one commentator (hint hint, Justin Gimelstob) to lean hard on the governing bodies to move this issue in the right direction. Imagine how powerful the ATP FedEx Reliability Stats could be if they integrated space into their stats by using Hawk-Eye data! Let’s hope that happens quickly. Then we can sit back and watch it open up a whole new world of tennis analytics, third party products and applications that will benefit the players, tournaments, the fans, the media and most of all the great game of tennis itself!

 * The Farmers Classic will not be returning to the ATP circuit in 2013. After 86 years, and being the longest running annual professional sporting event in Los Angeles, it ran its last event in 2012.