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.

Hawk-Eye

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.