One thing I want to correct you on is that Djokovic came back from 2 sets to love down at the 2011 USO and they split sets in the other two meetings.
Crap, I know what I did. I have scores for losses in reverse (long story, so I probably read all those scores wrong.
Remember, I told you I am glancing at data that I don't have filtered for this. I never thought about it before.
So I'm sure you are right about that.
Also, Federer wasn't weak in 2011 or 2014.
Weak as in no longer at his peak level, which should be obvious from any careful study of his stats.
He got to at least the SF in 3/4 majors in both of those years, made a GS final in both years and won two Masters tournaments in 2014. He may not have been at his peak or prime but I wouldn't call him weak.
You probably know the data on Djokovic better than I do, but you don't know it in depth re Fed.
In 2014, what you consider a strong year for him, his return game, again, was very poor for his standards on grass. His peak on grass was from 2003-2006. Even in 2007 it began to fall a little, but most years after that it was below his career average. Just as service stats are key for Novak (when he serves very well, he wins), the return is Fed's key, and when he returns well he wins.
When Novak is serving really well, and Fed is returning really well, flip a coin.
On clay Fed's return stats were 4th worst of his career in 2914, going back to 2002.
His return game on HCs was better but still a bit below his career average (never a good sign).
By the way, Fed was excellent in stats on HCs, in 2015, even on return. I would argue that he WAS near his peak that year, and Novak was simply too good.
I'm not saying that peak Fed beats peak Novak on HCs. To me at their peaks they were very, very close.