Novak Djokovic's path to another Australian Open title won't necessarily be an easy one for the No. 1 seed.
Through to third round after his four-set victory against American Frances Tiafoe on Wednesday, Djokovic's quarter of the draw includes 2020 US Open finalist Alexander Zverev and former Australian Open semifinalist Milos Raonic, and he could face fellow 2020 Australian finalist and reigning US Open champion Dominic Thiem in the semis before facing 20-time Grand Slam champion Rafael Nadal in the final.
That is a tricky path, yet Djokovic remained a +125 betting favorite to win the tournament per Caesars by William Hill (equivalent to 44.4% odds) at the start of the tournament. Tennis Abstract gave him a 36.6% chance of winning the tournament.
That's how good he is on hard courts, especially in Melbourne, where he has won eight of the past 13 Australian Opens.
Thanks to hard-court data from the past five years, it clearly shows us where and why Djokovic stands out. Charting data affirms what you already know: He wins primarily with defense and depth. However, it also tells you he might have the most underrated backhand and second serve in the game.
Let's dive into the numbers!
Djokovic's second act of dominance
The Serbian's first act, which spanned from 2011-16, saw him win 11 of 24 Slams and reach the finals in seven others. While he succumbed to injuries and poor form in 2017 and the first half of 2018, things clicked back into place after his surprising 2018 Wimbledon title run (he won as the No. 12 seed).
The 33-year-old has won five of the past nine Slams and reached the final in a sixth, and two of his four losses in this span included special circumstances -- he retired with a shoulder injury in the third set against Wawrinka in the 2019 US Open fourth round (he was admittedly down two sets to zero at the time), and he was defaulted from the fourth round of the 2020 US Open for hitting a linesperson with a ball.
He has faced a match point and lost in only two of his past 56 Slam matches, in other words. Excluding the default, he went 26-0 on hard courts in 2020.
He also hasn't lost in Melbourne since this second act began.
What match charting data reveals about Djokovic's greatness
Most sports offer a tradeoff of sorts: consistency vs. explosiveness.
Efficiency and consistency in a given sport offer sustainable success and predictive, long-term quality. Think of a football team that is good at staying on schedule, a baseball team that gets on base a lot, or Caroline Wozniacki going into full-on Human Backboard mode and returning every single ball.
Explosiveness and raw playmaking ability, meanwhile, offer the most direct way to winning a given point, game or match, albeit in a riskier, less reliable manner. Think of a quarterback heaving a deep ball, JR Smith randomly getting smoking hot for the New York Knicks in the early 2010s or Wawrinka finding his groove and pounding forehands through the court against even tennis' best defenders.
Most of a sport's greats combine these two traits -- they offer consistent explosiveness.
Roger Federer creating nonstop, error-free offense. Patrick Mahomes completing over 70% of his passes with some of the highest yards-per-completion averages in the NFL. Mike Trout leading the American League in both on-base percentage and slugging percentage.
Djokovic has thwarted this trend, however. He is not without his occasional explosiveness by any means -- after all, his most famous shot might be his match point in the 2011 US Open semifinal -- but to become maybe the greatest men's tennis player of all time, he didn't combine efficiency and explosiveness so much as he made himself the most consistent and efficient player we'll ever see.
Thanks to match charting data, we can dive deeper into what makes Djokovic's game so unique.
For years, Jeff Sackmann and an army of volunteers have been charting tennis matches as part of the Match Charting Project, which now features data on more than 8,000 matches, 1 million points and 5 million shots spanning from last week's WTA Gippsland Trophy tournament back to the 1959 Wimbledon men's and women's finals. It features 370 Djokovic matches (and counting), 514 Roger Federer matches and 397 Simona Halep matches, for instance, plus plenty of matches from retired greats: Andre Agassi (141), Steffi Graf (119), Boris Becker (91), Chris Evert (56), etc.
Although it doesn't include every match ever played (yet!), charting data allows us to move past the top-line stats -- winners, aces, unforced errors -- and into the nitty-gritty world of what actually derives strategy and determines wins and losses.
The return game
Key stats from this hardcourt sample:
Djokovic wins 41.0% of return points, compared to an overall average of 35.3% in the sample. He wins "key points" (break points, deuces, game points) 40.9% of the time vs. a 35.2% average.
His returns were categorized as "deep" -- between the service lines and the baseline -- 75.3% of the time (average: 66.5%) and "shallow" only 19.5% of the time (average: 22.3%).
In points decided within three shots, servers win only 60.6% of first-serve points and 58.1% of second-serve against Djokovic (averages: 66.4% and 58.1%, respectively).
First-serve points against Djokovic average 4.5 total shots, while second-serve points average 6.3 (averages: 3.7 and 5.1, respectively).
Depth is the most underrated weapon in tennis, and no one returns with depth and plays his way into a point like Djokovic. He neutralizes most serves with steady, deep returns, then massages the point in his favor. And his depth is universal:
Djokovic's percentage of "deep" returns:
74.1% against first serves
76.9% against second serves
75.1% of forehands
75.6% of backhands
76.8% from deuce courts
73.8% from ad courts
Match charters also record whether a given serve was returnable or "unreturnable" -- "where the returner fails to get a full racquet on the ball (including shanks), fails to get the return all the way to the net, or wildly misses." They record 73.6% of serves against Djokovic as returnable, which, compared to a 70.3% overall average in the sample, suggests his range is slightly better than normal. But he also wins 50.9% of points versus a returnable serve; of the 31 players with at least 1,000 charted returns in this sample, David Goffin (50.8%) is the only other player over 50%, and only Andy Murray (96.8%) and Alex De Minaur (96.2%) can top his 96.1% rate of putting returnable serves in play.
Opponents will serve to the body in key moments, but that's perhaps his biggest strength: 77.6% of these returns go to the deep part of the court. And while players will also try to attack your backhand, that doesn't work either -- he wins 44.5% of return points served to the backhand (sample average: 37.4%) and 51.8% of points with returnable serves (44.6%).
Basically, he gets to more serves, returns them with more consistency and depth, and waits you out.
The backhand and the forced error
On key points in the return game, Djokovic wins 9.7% of points with a forced error and loses only 14.3% with an unforced error (averages: 7.2% and 15.3%, respectively).
On game points in particular, where the opponent is attempting to close out a service game, Djokovic wins 12.5% of points with a forced error (average: 7.5%).
In most instances, a player's forehand is better than their backhand. One general way to look at who's controlling points is to simply look at a player's forehand-to-backhand ratio. Using the match-charting data in this five-year, hard-court sample, for instance, we see that while the average player hits a forehand 55.9% of the time in rallies, Federer is at 61.2%, Nadal 60.2%. Less successful players in the sample are primarily lower -- Francis Tiafoe is at 48.3%, John Millman 45.3%.
Djokovic is at only 50.9%, and it couldn't matter less. In points featuring a backhand shot, players only win 48.6% of the time on average, but Djokvoic wins 54.5%.
Combine this with the depth referenced above, and you see how frustrating it is to play against him. He sends everything deep into the court and gives you few balls to truly attack. He also turns matches into backhanded battles -- he hits backhands cross court and sends more forehands down the line (and toward a right-hander's backhand) than the normal player, and his backhand is far more consistent than anyone else's: only 6.8% of his backhands result in unforced errors compared to an overall average of 9.4%. Even if you are avoiding unforced errors, he leverages you into specific areas of the court and waits for you to press and try for too big of a shot. Djokovic is among the best in the world at this.
An underrated serve
Djokovic wins 58.7% of his second-serve points (average: 51.0%).
He wins 67.3% of first-serve points decided within three shots (average: 66.4%) -- and 66.5% of second-serve points decided within three shots (average: 58.1%).
He serves wide 45.3% of the time on deuce courts (average: 24.0%) and serves up the T 37.1% of the time on ad courts (average: 19.4%).
Djokovic's 2018 resurgence correlated almost perfectly with a remodeling of his serve -- or maybe I should say demodeling. After playing with a new service motion in an attempt to alleviate stress on his recently injured elbow, he moved back to his original serving motion.
The effects weren't really seen on first serves, where his numbers remain solid but unspectacular -- he won 73.4% of his first-serve points in this sample, compared to the 73.1% average. But his service motion is consistent enough that he barely takes anything off of his second serve, and he frequently uses a more attacking slice to the forehand than the typical, defense-friendly kick serve to the backhand. It has become one of the more aggressive, and effective, components of his game, and it comes with minimal downside.
Djokovic does double-fault more frequently than most elite players -- among the ATP top 10 over the past year, only Zverev double-faulted a higher percentage of the time (20.0% of second-serves) than Djokovic (10.4%). But most elites still double-fault on between 6-8% of second serves, so he's not that far off the normal pace, and it's clear the benefits have far outweighed the drawbacks. Over the past year, he has held serve 85.2% of the time on hard courts, 10th among the ATP top 50 players. Combined with his ever-elite return game -- he breaks serve 31.0% of the time on hard courts, second behind only Monfils -- that makes him pretty untouchable.
(Seriously, though, Zverev should probably take something off of those second serves.)
Tennis might have the smallest margins in any sport
Thiem won the 2020 US Open by winning just 55% of his points -- 11 of every 20. Djokovic, maybe the best hard-courter of all-time, won 55% of his hard-court points in all of 2020, 56% in 2019.
The difference in great and average play is winning one point or so for every 20 played, and Djokovic will go down as an all-time great, maybe the all-time great, by bending those tiny margins a tiny amount in his direction. He hits shots deeper than you, he makes fewer errors than you, and eventually, he breaks you.