The Masters in Bercy continues concerns over Novak Djokovic’s form going into the Tour Finals. With the loss to Marin Cilic in Paris and Andy Murray one win away from taking the World No. 1 spot, the 2016 season has raised many questions about Djokovic’s performance. While we see the indicators of a slump from his win record, we can’t know whether and how his game has actually changed— has he lost effectiveness on serve? or the forehand? in his shot accuracy off?
Although tennis fans will have to continue to wait to be able to have data on shot quality for all tour matches, the AO Leaderboard Series on this blog is trying to move in that direction by introducing of shot metrics from the Australian Open. This week looks at net clearance stats.
Net clearance refers to the distance between the ball and the net as it passes over the net. The distance from the net gives us insight into both the accuracy and spin of shots, with flatter shots tending to have less height when they pass over the center of the court. Thus, we would expect players who use less spin on a stroke and aim low will have the smallest net clearances in general.
The plot below shows the typical groundstroke net clearances for ATP players at the 2014 to 2016 Australian Open. The players are ranked by the height off net on the forehand (from smallest to largest). It also includes the backhand net clearance for comparison to the characteristics on the forehand. Note that the point sizes are scaled to the number of shots, so smaller points would indicate a player who has a smaller sample of shots (and greater uncertainty) in the summary.
There are about 20 players whose forehand is typically within 0.6 meters of the net (the smallest distance in the game). In this group are a number of the games biggest servers— Milos Raonic and John Isners— as well as players known for fast and flat forehands— Juan Martin Del Potio, Lukas Rosol, Roger Federer and Novak Djokovic. We shouldn’t be surprised to see Rafael Nadal toward the bottom of the pack with an average net clearance of 0.78 meters, a height that aligns him with players like Domonic Theim and Tommy Robredo.
We can see from the swirl of points around the forehand that the backhand characteristics can differ wildly from the forehand. This suggests some different strategic patterns in the style of shots with some players having a flat forehand and spinny/looser backhand (Jo-Wilfried Tsonga and Jeremy Chardy), players who play fairly flat on both strokes (Bernard Tomic and Andreas Seppi) and players who tend more on the spinny side on both (Lleyton Hewitt and Andy Murray). And, depending on the mix of flat and spinny shots for each stroke, there could be numerous variants among these.
On the women’s side, we see several of the big and flattest hitting players in the top 10 of forehand net clearance: Madison Keys, Petra Kvitova, and Garbine Muguruza. Each of the players in this group have an average height off net of 0.55 meters or less. Female players competing at Grand Slams are more likely to have looping shots on both the forehand and backhand in contrast with male players. Sara Errani and Saisai Zheng are two players who have managed to have success on tour despite having some of the loopiest forehands in the game.
As we observed with the ATP, there is little agreement between the height characteristics of backhands and forehands for most WTA players. Some interesting exceptions are Serena Williams, Maria Sharapova and Joanna Konta whose average height on the forehand and backhand are virtually indistinguishable.