Of course, Federer’s 2004-2009 peak was higher than Djokovic’s 2018-2023 peak. Federer was in his mid-20s and Djokovic is in his mid-30s. If that comparison is even in doubt, that would be very sad for Federer. On the other hand, Djokovic’s 2011-2016 peak is arguably higher than Federer’s 2004-2009 peak. Both ATP points and more especially Elo, which takes into account level of competition, bear this out. In any case, all three 6-year periods are astounding numbers and achievements. The point that almost everyone here seems to be missing is that Djokovic didn’t have one of these stretches of greatness. He had TWO.
The cause of the differences in the numbers are clear. Djokovic’s 2018-2023 stats are from an older player who played a smaller schedule and saved himself for slams and had a weaker field (just not as weak as his detractors claim nor as strong as his supporters claim). This period was also significantly disrupted by a pandemic and a freak default that likely cost Djokovic between 2 to 4 additional slams. Federer’s 2004-2009 seasons have slightly better numbers than Djokovic’s 2011-2016, and that’s explained by Federer only really having Nadal, baby Novak, and baby Murray as heavy competition during that period while Djokovic had Nadal, Federer himself, peak Murray, and peak Wawrinka in 2011-2016. Despite having 1 more slam in 2018-2023 than in 2011-2016, Djokovic clearly achieved more in 2011-2016 due to being better everywhere else but slams. Like Federer’s 2004-2009, Djokovic’s 2018-2023 only really had Nadal, Medvedev, and recently Alcaraz as heavy competition.
What people are missing about 2018-2023 is that while the competition is easier, Djokovic is older, so for him to be getting 12 slams in his 30s is still a massive achievement. Again though, Djokovic hasn’t declined as much as his detractors say but has declined more than his supporters admit.
I’m going to write something that Federer fans should love. If 2004-2009 Federer switched places with 2011-2016 Djokovic, meaning Federer was 22 in 2011, he would have performed about as well as Djokovic and achieved about the same numbers, not just from 2011-2016 but from 2011-2023. The reason for this is that there is just not a huge difference between their levels as much as one side or the other may want to believe. The only qualification I would make is that Federer always had more trouble with Nadal than Djokovic and that would likely still be the case. Sure, Federer may take advantage of Nadal’s dip during 2015-2016 and own Nadal on hard courts thereafter, but he’ll still likely never beat Nadal at RG. Matchups matter. And as great as 36-year old Federer was in 2017/2018, he still wasn’t quite as great as 36-year old Djokovic was this year (45 wins to 5 losses, 27-1 at slams).