Djokovic is in a slow decline, but his fans don't acknowledge it yet

[Gary Duane]

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Here is the data, and it shows his fading ability to return compensated for improving service. This is not a troll thread, an attack or an attempt to invalidate any of his accomplishments.

In fact, the way he is losing some of his defensive ability is very slow, very subtle and may be the slowest decline we've ever seen in the history of tennis.

Aside from 2006, when he was just breaking into the ATP, his worst year ever for serving on hard was 2010, where he barely got over 82% of service game for the year. In 2011, his miracle returning year, he was very close to 85%. This year, so far, he is at very close to 91%. That's a 6% net gain on the service game, which is amazing. But his return game percentage is currently at 28%.

28% would be a dream come true for most top players, but for him it's not only a 13% drop from 2011, his miracle returning year, it's 4% below his career average.

He will have to raise that this year to keep the same dominance he's had in the past. Does that mean he's no longer the best hard court player in the world? No, because there is so far no one who is approaching that magic 60% number for all games, so he's still the guy to beat.

But keep in mind that his career average on hard is 59.76% of all games, and that average includes not only 2017, his worst year since 2006, but also every year up to 2010. So when his yearly average fall below his career average, that's a decline. Please be aware that a decline for Djokovic is at the point mostly superior to everyone else out there, so keep it in perspective.

Just remember that anything under 30% of games won on return is well below his career average, a whopping 32%. So look carefully this year to see if that number goes up, or if it goes lower.

Remember: all aging players have a decline in defensive skills. It's just a matter of how fast it happens, and how long it takes before they fall to a point they can no longer compensate.

 

[Gary Duane]

Unfortunately the code that used to work here for sharing pictures no longer works here from Dropbox, but you should be able to see the data. Red is below career average. Blue is above.

Note the high numbers after 2017, showing that his service game has improved. So far it is at an all time high this year, but that will be inflated because of a relatively fast court, which also deflates his returning. I expect the service percentage number to drop by 2-3% by the end of the year, so keep your eye on the return number. If it goes back to 30% or above, he will be fine. But if that number drops below 28%, it's a proof of a decline.

 

[Lew II]

He won 6 of the last 10 Slams, which could've been 8 of the last 11 if Wimbledon was held and he wasn't DQed at the USO.

In Grand Slams since 2016 he had some of his highest win percentages in returning games:

2012 - 40.3%
2011 - 38.8%
2019 - 36.4%
2020 - 36.0%
2016 - 35.9%
2017 - 35.7%
2018 - 35.0%
2010 - 32.4%
2014 - 32.2%
2015 - 31.2%
2013 - 30.9%
2008 - 29.6%
2021 - 29.6%
2009 - 29.5%
2007 - 25.6%

 

[Red Rick]

I don't really doubt he's in a slow decline. I think many acknowledge thhat indirectly when they sledge the Nextgen for failing to beat him.

I do think he tries less hard in smaller tournaments than before and that will also depress his stats a little bit.

Funnily enough, Fed had his last really big stat year 6 years ago, at the same age.

 

[Lew II]

Unfortunately the code that used to work here for sharing pictures no longer works here from Dropbox, but you should be able to see the data. Red is below career average. Blue is above.

Note the high numbers after 2017, showing that his service game has improved. So far it is at an all time high this year, but that will be inflated because of a relatively fast court, which also deflates his returning. I expect the service percentage number to drop by 2-3% by the end of the year, so keep your eye on the return number. If it goes back to 30% or above, he will be fine. But if that number drops below 28%, it's a proof of a decline.

Proof of a decline will be when he doesn't win Slams anymore.

 

[Crazy Finn]

Right now, Djokovic's decline is slower than the overall declining of his competition.

 

[ABCD]

I have little bit different view than my friend Gary. I believe that Djokovic is improving, just the field is getting stronger making his statistics worse.

 

[Sport]

He won 6 of the last 10 Slams, which could've been 8 of the last 11 if Wimbledon was held and he wasn't DQed at the USO.

In Grand Slams since 2016 he had some of his highest win percentages in returning games:

2012 - 40.3%
2011 - 38.8%
2019 - 36.4%
2020 - 36.0%
2016 - 35.9%
2017 - 35.7%
2018 - 35.0%
2010 - 32.4%
2014 - 32.2%
2015 - 31.2%
2013 - 30.9%
2008 - 29.6%
2021 - 29.6%
2009 - 29.5%
2007 - 25.6%

Good comeback.

 

[TripleATeam]

Of course he is, he's clearly not the same player he was in 2015, especially in terms of consistency day-in, day-out. It's just he's doing very, very well for his age. He's coming up with improvements in other places of his game to make up for his slower movement and not quite-as-good baseline play (by which I mean he's improved his serve big time).

 

[aldeayeah]

2021 results may be a bit skewed by the court speed, we haven't seen him on the medium/medium-slow speed courts yet.

Also IMO he coasts/cruises on his serve much more now, saving energy instead of going for multiple breaks.

Combined with mediocre competition, the end result is that his decline is barely noticeable

 

[daphne]

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Here is the data, and it shows his fading ability to return compensated for improving service. This is not a troll thread, an attack or an attempt to invalidate any of his accomplishments.

In fact, the way he is losing some of his defensive ability is very slow, very subtle and may be the slowest decline we've ever seen in the history of tennis.

Aside from 2006, when he was just breaking into the ATP, his worst year ever for serving on hard was 2010, where he barely got over 82% of service game for the year. In 2011, his miracle returning year, he was very close to 85%. This year, so far, he is at very close to 91%. That's a 6% net gain on the service game, which is amazing. But his return game percentage is currently at 28%.

28% would be a dream come true for most top players, but for him it's not only a 13% drop from 2011, his miracle returning year, it's 4% below his career average.

He will have to raise that this year to keep the same dominance he's had in the past. Does that mean he's no longer the best hard court player in the world? No, because there is so far no one who is approaching that magic 60% number for all games, so he's still the guy to beat.

But keep in mind that his career average on hard is 59.76% of all games, and that average includes not only 2017, his worst year since 2006, but also every year up to 2010. So when his yearly average fall below his career average, that's a decline. Please be aware that a decline for Djokovic is at the point mostly superior to everyone else out there, so keep it in perspective.

Just remember that anything under 30% of games won on return is well below his career average, a whopping 32%. So look carefully this year to see if that number goes up, or if it goes lower.

Remember: all aging players have a decline in defensive skills. It's just a matter of how fast it happens, and now long it takes before they fall to a point they can no longer compensate.

Have you noticed that his serve has improved a lot? Can it be a sign of a different strategy? How do we know what his planning and periodisation is like especially during this COVID19 mayhem?

 

[CYGS]

So? Are you expecting him to have no decline at all? Speaking of delusional.

 

[daphne]

Djokovic is in a slow decline, but his fans don't acknowledge it yet


That's what the title should have been if you really wanted to be seen as objective. You can notice whether he is in a slow decline or not by analysing the stats but YOU CAN NOT know whether his fans acknowledge it or not as there are no stats for it.

Comprende, no?

 

[Crazy Finn]

Of course he is, he's clearly not the same player he was in 2015, especially in terms of consistency day-in, day-out. It's just he's doing very, very well for his age. He's coming up with improvements in other places of his game to make up for his slower movement and not quite-as-good baseline play (by which I mean he's improved his serve big time).

I'd agree with all of that.

It's almost like after being on the tour for 15 years and playing over a thousand matches have helped him figure a few things out...

He also seems to think about things more analytically than players of the past. That ESPN article was interesting.

Have you noticed that his serve has improved a lot? Can it be a sign of a different strategy? How do we know what his planning and periodisation is like especially during this COVID19 mayhem?

I think that's pretty likely. I'm sure he looked at his serve as something that still had some room to improve and - with the right approach - didn't put more strain on him physically.

 

[GoldenMasters]

Of course he is in a decline and his sane fans do acknowledge it. Only fans of other players like StrongRule rage how he is still at his peak.

 

[Bumbaliceps]

Considering the numerous lows he had at the AO, I'm not sure the return games percentage is that significant. I would say the lower numbers are due to him having bad moments in this tournament. I thought his returning in the final was simply amazing.
But anyway I agree he is declining from the baseline, and I think it is due to physicality, as shown by his difficulties against PCB and RBA who get every ball back, but not in the slightest due to the return as a shot.

 

[Gary Duane]

He won 6 of the last 10 Slams, which could've been 8 of the last 11 if Wimbledon was held and he wasn't DQed at the USO.

In Grand Slams since 2016 he had some of his highest win percentages in returning games:

2012 - 40.3%
2011 - 38.8%
2019 - 36.4%
2020 - 36.0%
2016 - 35.9%
2017 - 35.7%
2018 - 35.0%
2010 - 32.4%
2014 - 32.2%
2015 - 31.2%
2013 - 30.9%
2008 - 29.6%
2021 - 29.6%
2009 - 29.5%
2007 - 25.6%

Those are good stats, for sure.

2007
2008
2009
2010
2017
2006

These are the years he was around 58% of games or lower for the year. Only in 2008 of those years did he win a hard surface slam.

That's doesn't prove it's impossible again, just that under 58% is far more likely.

Let's revisit this after 2021, early in 2022. I think he has a higher gear now, but I wager that when he falls below 58% of games for the year he'll stop wining hard slams. That may not happen this year, next year or even the year after. I'm not predicting. I'm just saying that for the rest of the open era you could always see declines when in games paralleling no longer winning slams for ATGs.

I have the stats for games won by all slam winners for the entire open era. I see no direct conclusion from those numbers other than that number is higher for the guys who won a ton of slams when averaged for careers.

 

[toby55555]

It will be interesting to see who next joins Murray and Federer in the shadows. It was always though Nadal would be first to go because of the physicality of his game but he’s still going strong a year older than Novak and Andy.

 

[Crazy Finn]

It will be interesting to see who next joins Murray and Federer in the shadows. It was always though Nadal would be first to go because of the physicality of his game but he’s still going strong a year older than Novak and Andy.

Nadal has clay which helps him out physically. He's still dangerous on hard courts, but I don't think he's what he used to be on hard courts. We'll see at USO this year, that's always been friendlier to Rafa than AO.

 

[Raul_SJ]

His game might be in decline but it is possible that Djoker is serving as well as ever.
That aspect of his game may not be in decline. Somebody do the needful and check the stats. Believe Djoker led the AO in aces.

 

[Gary Duane]

Considering the numerous lows he had at the AO, I'm not sure the return games percentage is that significant. I would say the lower numbers are due to him having bad moments in this tournament. I thought his returning in the final was simply amazing.
But anyway I agree he is declining from the baseline, and I think it is due to physicality, as shown by his difficulties against PCB and RBA who get every ball back, but not in the slightest due to the return as a shot.

The AO numbers tell us very little. He won, and that's all that is important. But note also that he won over 91% of his service games, and fans should be hopeful that he keeps that up.

I have no dog in this hunt. I'm reporting numbers, and those numbers have been incredibly accurate for all of the open era and showing peak years.

60% of games in a year is a magic number. It is rare that any player who gets that high not only does not dominate that surface that year but also gets a slam. With two hard slams each year it means that over 60% today usually means at least one of the two possible slams. The exception is when there are two players doing it.

You can spot in a hearbeat who is in that rare atmosphere. You see something like 88/32, like 88% of service games and 32% of return games. When you see players at 32% or above, if they are not winning slams they are well below the 88%, for instance Murray. It's not foolproof, but it's close to it. Wawrinka is the biggest exception I've ever seen. He absolutely does not fit that mold.

 

[Gary Duane]

Have you noticed that his serve has improved a lot? Can it be a sign of a different strategy? How do we know what his planning and periodisation is like especially during this COVID19 mayhem?

Yes. His serve has improved tremendously since 2011, but you can't conclude it is even better until we get through the year. At the moment he's at an all time high, but things go up and down from tournament to tournament. The decline in returning is very small, so if the serve stays high, he could have a few more years. To be honest, at this point I'll be every surprised if he does not tie or win the slam race.

The problem with Fed is that because his serve was always so great, there was really no place for him to go. When the return stats started to lower, he couldn't dominate. He got a second strong period because of the racket, which gave him tools that he did not have when younger. But even with these tools he never got back up to his peak in returning.

People forget that that going from 41 even down to 32 is a 9 point drop. The reason 2015 Djokovic equalled or beat 2011 Djokovic is that his serve improved incredibly. 2011 Djokovic with today's serve I think would have gotten the grand slam in 2011, and he would have had the highest stats for the year we've ever seen.

 

[Born_to_slice]

His return is holding pretty steady when you account for racquet modifications towards lighter weight and more open string pattern. He's probably lost a couple of milliseconds of reaction time tho.

His stamina has definitely declined some, which is only natural but I like more aggressive approach and improved serve.

 

[junior74]

I have little bit different view than my friend Gary. I believe that Djokovic is improving, just the field is getting stronger making his statistics worse.

 

[Gary Duane]

His return is holding pretty steady when you account for racquet modifications towards lighter weight and more open string pattern. He's probably lost a couple of milliseconds of reaction time tho.

His stamina has definitely declined some, which is only natural but I like more aggressive approach and improved serve.

I have a lot more numbers. The ones I have show that aggressive players don't need as many games to win. The logic is probably that top servers don't have to return as aggressively until they are in trouble, and that gives them an extra gear. Sampras had it Fed had it. I don't think Djokovic did when he was younger, which is why even with such absurdly high numbers in 2011 he was not as dominant as in 2015. I think he very much DOES have that higher gear now, and that explains perhaps is lower dominance is less important tournaments. He doesn't need them now. Even winning the WTF or any 1000 is just icing on the cake. He needs more slams.

So increased aggressiveness and shortening points is how aging ATGs stay on top or nearly on top a bit longer. For sure hs is doing the right thing. That said, I still think that if he falls below 58% of games, it will be much harder to win slams, so that's something to watch out for. It doesn't really matter where the decline happens, and no one, no matter how clutch, can continue winning big events when those numbers continue to fall. The exception is when an ATG, close to retirement, makes one last stand, as Sampras did for his last slam. That's can't be predicted. That's when someone aging summons every bit of experience and simply leaves it all on the court.

 

[Sunny014]

Considering the numerous lows he had at the AO, I'm not sure the return games percentage is that significant. I would say the lower numbers are due to him having bad moments in this tournament. I thought his returning in the final was simply amazing.
But anyway I agree he is declining from the baseline, and I think it is due to physicality, as shown by his difficulties against PCB and RBA who get every ball back, but not in the slightest due to the return as a shot.

Only 1 person has not declined from the baseline.

The Great Rafael Nadal !!!!

 

[Gary Duane]

I have little bit different view than my friend Gary. I believe that Djokovic is improving, just the field is getting stronger making his statistics worse.

But the problem here is that it is chicken/egg. Remember, at all times the whole "weak/strong" era argument assumes that except for the top players everyone else is much stronger or weaker, across the board. With that logic we have to assume that competition was never higher, things were never closer than in the 90s, because that's when we saw the most upsets. And that for years now, because things have never been more predictable, with always the same guys winning, competition has been the weakest.

The problem with that is that there are no proofs. There are no objective measurements to prove that. It's not like swimming or running, where there are records set, and you can see how many people are getting faster or equaling past records. It's not like bowling, where the best you can do is bowl a perfect game, so you can see how many people do it, and how often.

Even with aces you don't know how many of them are because the serves are so good or because the returners are weak.

The only absolutes I know of are service speed and things like Hawkeye measurements. Like they show the average return position for players, and if its getting closer to the line. I guess you can measure average depth, and of course we know about spin, how many revolutions. But everything except the serve is reactive, based on what is hit to you. So everything is relative.

That leads to daily food fights about weak eras vs dominant players.

In one sentence:

Is player A "that good", or are all the other players "that bad"?

I will never go there, because it's just an OCD loop.

 

[helterskelter]

I don't really doubt he's in a slow decline. I think many acknowledge thhat indirectly when they sledge the Nextgen for failing to beat him.

I do think he tries less hard in smaller tournaments than before and that will also depress his stats a little bit.

Funnily enough, Fed had his last really big stat year 6 years ago, at the same age.

All aging players cease trying as hard in smaller tournaments, but that is their own implicit acknowledgement of decline, as they know that they have to pace themselves more than they used to. Even if it's for reasons of lost interest, that is itself a form of decline (it is what ended the careers of Borg and Wilander and pretty much McEnroe, too).

 

[TripleATeam]

Only 1 person has not declined from the baseline.

The Great Rafael Nadal !!!!

If you're a Nadal fan, that's not being very kind to Nadal. Just look at him a decade ago.

 

[Red Rick]

I have a lot more numbers. The ones I have show that aggressive players don't need as many games to win. The logic is probably that top servers don't have to return as aggressively until they are in trouble, and that gives them an extra gear. Sampras had it Fed had it. I don't think Djokovic did when he was younger, which is why even with such absurdly high numbers in 2011 he was not as dominant as in 2015. I think he very much DOES have that higher gear now, and that explains perhaps is lower dominance is less important tournaments. He doesn't need them now. Even winning the WTF or any 1000 is just icing on the cake. He needs more slams.

So increased aggressiveness and shortening points is how aging ATGs stay on top or nearly on top a bit longer. For sure hs is doing the right thing. That said, I still think that if he falls below 58% of games, it will be much harder to win slams, so that's something to watch out for. It doesn't really matter where the decline happens, and no one, no matter how clutch, can continue winning big events when those numbers continue to fall. The exception is when an ATG, close to retirement, makes one last stand, as Sampras did for his last slam. That's can't be predicted. That's when someone aging summons every bit of experience and simply leaves it all on the court.

While his movement is declining, it's still the best in the world, so I tink if he can improve his forehand into a bigger weapon it makes everything so much easier for him. Every annoying matchup for him is own to being stalled or overpowered on that side.

 

[Red Rick]

All aging players cease trying as hard in smaller tournaments, but that is their own implicit acknowledgement of decline, as they know that they have to pace themselves more than they used to. Even if it's for reasons of lost interest, that is itself a form of decline (it is what ended the careers of Borg and Wilander and pretty much McEnroe, too).

Fed keeps stat padding Basel tho

 

[Sunny014]

But the problem here is that it is chicken/egg. Remember, at all times the whole "weak/strong" era argument assumes that except for the top players everyone else is much stronger or weaker, across the board. With that logic was have to assume that competition was never higher, things were never closer than in the 90s, because that's when we saw the most upsets. And that for years now, because things have never been more predictable, with always the same guys winning, competition has been the weakest.

The problem with that is that there are no proofs. There are no objective measurements to prove that. It's not like swimming or running, where there are records set, and you can see how many people are getting faster or equaling past records. It's not like bowling, where the best you can do is bowl a perfect game, so you can see how many people do it, and how often.

Even with aces you don't know how many of them are because the serves are so good or because the returners are weak.

The only absolutes I know of are service speed and things like Hawkeye measurements. Like they show the average return position for players, and if its getting closer to the line. I guess you can measure average depth, and of course we know about spin, how many revolutions. But everything except the serve is reactive, based on what is hit to you. So everything is relative.

That leads to daily food fights about weak eras vs dominant players.

In one sentence:

Is play A "that good", or are all the other players "that bad"?

I will never go there, because it's just an OCD loop.

Sir,

It is possible that fast courts in the 90s created more upsets ?
With decline in returning and reflexes of people in late 20s then it only could be worse if a 22 years belts the ball past you with low bounce.

Now in this era ball is so high, so lot of reaction time for the likes of Nadal/Novak to continue their stints at the top.

 

[Sunny014]

If you're a Nadal fan, that's not being very kind to Nadal. Just look at him a decade ago.

Not a big fan of him but he still is powerful than the rest of the field.
Yes his arm was more powerful 10-12 years back, that is certain.

 

[helterskelter]

Fed keeps stat padding Basel tho

I said "aging" for a reason, though, rather than "old."

Normal trajectory is: at some point, a player ceases to do as well in minor events but still does well in majors for a while, because they can pace themselves. Then their decline becomes more severe and they can't do as well in majors anymore. At that point, they characteristically start doing better in some minor events again, because they now focus on them so that they can at least win something.

This is one reason why Murray's early head-to-head against Federer was better than his later one - most of their early matches were in MS1000 events that Murray took fully seriously and Federer did not. Similarly with Medvedev's recent success against Djokovic.

 

[Red Rick]

Sir,

It is possible that fast courts in the 90s created more upsets ?
With decline in returning and reflexes of people in late 20s then it only could be worse if a 22 years belts the ball past you with low bounce.

Now in this era ball is so high, so lot of reaction time for the likes of Nadal/Novak to continue their stints at the top.

How often did Sampras get upset at the hyper fast grass?

If anything it's changegs in court speeds that cause upset

 

[weakera]

If he can flip the switch in finals, he will continue to pile up slams, but there is no doubt that he is more vulnerable in the first week and a half than perhaps ever before.

 

[Gary Duane]

While his movement is declining, it's still the best in the world, so I tink if he can improve his forehand into a bigger weapon it makes everything so much easier for him. Every annoying matchup for him is own to being stalled or overpowered on that side.

I'm talking about a decline in numbers. A lot of you claim you can see this stuff with the eye test, and I can't. It's too small. However, I do see things perhaps others don't see. Remember when he changed his windup, when he was injured? That windup almost went back to what it was, but there is still a difference, and I can see it.

Better FH means better aggression. It's important for aging players to end points faster. And yes, no one moves like him, and I think no one ever has. That ability to stretch is super human. It allows him to reverse directions faster. I'm not predicting when or how he will lose dominance. I'm only suggesting that when it happens, you'll see it in the numbers.

 

[Red Rick]

I said "aging" for a reason, though, rather than "old."

Normal trajectory is: at some point, a player ceases to do as well in minor events but still does well in majors for a while, because they can pace themselves. Then their decline becomes more severe and they can't do as well in majors anymore. At that point, they characteristically start doing better in some minor events again, because they now focus on them so that they can at least win something.

This is one reason why Murray's early head-to-head against Federer was better than his later one - most of their early matches were in MS1000 events that Murray took fully seriously and Federer did not. Similarly with Medvedev's recent success against Djokovic.

Yeah.

I think Fed also just has a style that's more economical to cruise through weaker fields, and I wonder if he's started trying to get breadsticks to preserve more energy.

 

[Born_to_slice]

28% would be a dream come true for most top players, but for him it's not only a 13% drop from 2011, his miracle returning year, it's 4% below his career average.

Account for the fastest AO in recent history and playing a lot of big servers in this draw. It's clay where return games won stats is inflated. Last year Djokovic had 40%, which is highest since 2016 and even higher than 2011 on clay.

 

[Bartelby]

Your argument is a marvel of statistical eonomy.

Only 1 person has not declined from the baseline.

The Great Rafael Nadal !!!!

 

[Gary Duane]

Account for the fastest AO in recent history and playing a lot of big servers in this draw. It's clay where return games won stats is inflated. Last year Djokovic had 40%, which is highest since 2016 and even higher than 2011 on clay.

Faster AO will not be important for year stats unless someone only plays that event. That's why I'm sure Novak will end up more like around 88%

Numbers go all over the place for single events. But clay has higher total numbers for games and always has. That's why if you look at Nadal and Borg on clay and how many games they won, they look better than everyone else. Not because they are, only because they were/are the best on that surface. Games were always lowest on grass, and still are. So serve goes highest on grass, return is lowest on grass, and total numbers are lowest on grass.

 

[Gary Duane]

Sometimes nonsense is concise.

Your argument is a marvel of statistical eonomy.

 

[Sunny014]

How often did Sampras get upset at the hyper fast grass?

If anything it's changegs in court speeds that cause upset

Wimbledon faster like 90s surely won't be liked by Nadal.
No idea what Djokovic will feel, I think even he won't like, upset chances for them increase a lot.

Sampras and Federer were good at anticipating the ball on grass and themselves had goat serves .....

 

[Born_to_slice]

Faster AO will not be important for year stats unless someone only plays that event. That's why I'm sure Novak will end up more like around 88%

Numbers go all over the place for single events. But clay has higher total numbers for games and always has. That's why if you look at Nadal and Borg on clay and how many games they won, they look better than everyone else. Not because they are, only because they were/are the best on that surface. Games were always lowest on grass, and still are. So serve goes highest on grass, return is lowest on grass, and total numbers are lowest on grass.

I was talking about return stats. It's important who do you play. It's not same if you play Raonic and Fritz or Nishioka and Schwartzman.

 

[ewiewp]

Certain physical abilities of a human starts to decline as soon as your turn 20.
There is no question he is declining in one way or another.

 

[socallefty]

All the matches at the ATP Cup and the AO were played on a very fast court (fastest ever at AO according to Djojovic) where you would expect the return numbers to be down, In addition, Djokovic had an abdominal tear for the last 4.5 matches and could not play as well from the baseline - he looked completely normal only in the final ever since the injury occurred. He was getting outrallied by Zverev from the baseline earlier and survived only by clutch serving.

Of course, his return numbers are down as he couldn’t play as well as usual. Luckily his serve was on fire and he won the AO because he served great to get into the final. Let’s evaluate how his return numbers look like once he recovers from his injury and plays more tournaments. Meanwhile, I doubt that he is going to start serving worse, although the service hold % will go down on slow clay just like it will for other players also.

I don’t doubt that he is in slow decline as his movement is slower as he ages and he seems to play passively in too many matches in the last year. But, he just showed that he can win a Grand Slam even when injured and he won two Masters tournaments at ‘Cinci’ and Rome not too long ago. So, he won big titles on slow hard, clay and fast hard courts even when not at his best - then in the AO final, he looked like vintage Novak in top form. No wonder his fans are not too worried.

 

[yokied]

But he’s gradually becoming Fed with an ugly backhand, so he can’t be declining. He just keeps improving right? Right?

 

[InsideOut900]

Remember: all aging players have a decline in defensive skills. It's just a matter of how fast it happens, and now long it takes before they fall to a point they can no longer compensate.

While this holds true, the biggest decline seems to be in his offensive ability.

His defensive skiils have declined linearly or he is even ahead of the curve, perhaps.
His speed around the court is still remarkable and his shot tolerance is alright honestly, declined, but still alright.

However, his offensive BH is nowhere to be found in big matches and his injections of pace on the FH are good, but not very regular or very consistent.

During his last great/peak performance (AO 19 F), what stood out were his offensive capabilities. His defensive capabilities weren't exactly peak that day, nothing to compare to AO 11 or AO 16 Djoker, but his ability to hit winners and aggressive rallying was off the charts.

In the meantime, nothing to compare that performance with offensively, but I would wager he can still come close to the defensive capabilities he had at AO 19.

Another example of decline on offensive baselining is Wimbledon 18 vs Wimbledon 19. Wimbledon 18 had some of the most brutal rallies you are gonna see out there, while in 2019 he tried to outgrind and servebot people on grass.

The last observation I would like to make, his return seems to be more up and down these days, but his peak returning as of 2021 is still incredible. Reflexes and depth of return have barely decline imo, but he shows that slightly less.
His returning at YEC 2020 against Medvedev, Zverev and Thiem was bordeline tragic. By comparison, his returning in the last 2 sets vs Raonic, against Zverev and in the AO F vs. Med was solid.

Another example of decline in offensive capabilities, he legit couldn't hit through Nadal in the FO final. Djoko made it look like he was facing 2006-2007 Nadal in MC or 2008 FO.
He was hitting flat and straight up ballbashing because he didn't have the explosiveness to go for heavy FHs, with lots of topspin, to push Nadal back and draw weak responses, one of the key aspects in his performance in 2013 FO SF or 2015 FO QF, two of his best matches vs Nadal at FO.

So tldr: His return is more up and down, BH down the line is less potent and in gradual decline, which honestly started way back in 2015 and he can no longer inject pace as consistently as before.

By compensation, his serve is the best it has ever been right now.

 

[Sysyphus]

All the matches at the ATP Cup and the AO were played on a very fast court (fastest ever at AO according to Djojovic) where you would expect the return numbers to be down, In addition, Djokovic had an abdominal tear for the last 4.5 matches and could not play as well from the baseline - he looked completely normal only in the final ever since the injury occurred. He was getting outrallied by Zverev from the baseline earlier and survived only by clutch serving.

Of course, his return numbers are down as he couldn’t play as well as usual. Luckily his serve was on fire and he won the AO because he served great to get into the final. Let’s evaluate how his return numbers look like once he recovers from his injury and plays more tournaments. Meanwhile, I doubt that he is going to start serving worse, although the service hold % will go down on slow clay just like it will for other players also.

If you look at the spreadsheet poasted in the OP, I think it's clear that a decline in return stats for Novak is a longer trend and not just an isolated 2021 phenomenon. He hasn't had a season with return stats above his career average on HC since 2016.

How this will develop through, say, these next couple of season is an open question of course, as is the question of how much it will affect his slam-winning chances, seeing as he seems to raise his game for the majors these days.

 

[Hitman]

The most important thing is, he is declining significantly slower than his main rivals. Novak looks like he has several years left to keep winning slams. Whether that happens or not is another question, but tennis and fitness wise, he is still better than his peers.