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In other words, Federer had to be at his absolute best to beat Djokovic, who wasn't at his best, in 4.

Of course you'd think that. Let's look at some stats, shall we?
Djokovic in RG 2011 SF hit 40 winners and 41 UE, for the 2016 final the numbers are 41 and 37 respectively. The 1st serve percentage is very close too, 67% in the SF and 69% in the final today. However, when you consider the fact that in the set st 11 SF Fedehadn't nd Djokovic played a tota. l of 309 points, andup n the final today onlyover. . . points were playetrying puts the numbers into perspective. Besides, Djoevery almost choked the 4th set lead against Murray who . was really poor. The only thing Djokovic did significantly better in today's final is net play. Novak approached a lot more and won a much higher percentage at the net (78% vs 53%). But all in all, there's not much between Djokovic's performance in 2011 and his performance today. At least not as much, as you make it out to be.
Djokovic in the RG 2011 SF didn't play a bad match. In fact, he was playing pretty damn well. The thing is, when you're facing
that Federer across the net, playing well is not enough to win. Though it was enough to completely dominate Murray, who served 50% of 1st and made 39 UE to 23 winners (10 of which he hit in the 1st set), so no wonder you're impressed.