I appreciate the criticism, and there is something to it in that my method is inexact. However, because the performance of Djokovic's competitors are that much signficantly better than Federer's competitors, the point still stands that Djokovic is not playing in a weak era.
I disagree. The results are flawed and therefor the conclusion si flawed too. Before trying to compare differents eras, which is very complicated, your method should at least be able to identify the most dangerous competitor for Djokovic/Federer, and it fails to do it:
You have Berdych more dangerous than Cilic, Ferrer more dangerous than Wawrinka, and worst of all, Murray and Federer more dangerous than Nadal, who won only 5 slams, beating Novak 4 times! Do you think this describe accurately the threats for Djokovic?
Likewise, Safin and Djokovic are ranked too low among Federer's competition. After all they did defeat him twice.
So what your method do is measure who are the players who achieved the most in slam in these two time span, with a slightly biais toward consistency (in your ranking, a player who win a slam earn 7* more than a player who lose in the 1st round. In the atp ranking, he earn 20* more). It's totally correct to say that the player who have achieved more is the better player. But it's not automatically correct that he was the biggest threat. Players like Cilic, Safin, Del Potro Wawrinka, who are very erratics, are most of the time non-factor, but in some tournaments they win it all, unlike players like Ferrer or Murray or even Federer today. For a champion, if Djokovic play Cilic on fire at one tournament and Wawrinka on fire in next one, he face a harder competition than he face twice Murray or Ferrer.
Finally you will never convince anyone that we aren't now in a weaker era (not weak in absolute terms), in comparison with the late 2000's and early 2010's when Federer and Nadal where much better player than now. Both Federer and Djokovic have played in weaker eras and stronger eras, and both of them have been able to capitalize on the weaker one to win many slams. They didn't have the opportunity to play in weaker eras because they were lucky. They had the opportunity to play in weaker eras (once again relative to other eras) because they played at a very high level of a very long time, moreso than most other all time greats. More than Sampras, more than Borg, more than Agassi, more than Nadal, etc.
At the end of their career, it will be laughable to argue that they faced easy competition when Federer had to compete with Nadal and Djokovic in the second part of his career, when he was still playing at a level high enough to defeat more normal finalists (like Murray). Likewise Djokovic was playing at a slam winning level since 2007, and all he had to show for it are SF appearance because Nadal and Federer.