Hall of Fame
Yeah, @NatF's reductio ad absurdum earlier on pretty much kicked that dead horse up the arse.2006 Federer couldn't have improved much since that was his absolute peak. Same for 2011 or 2015 Djokovic. It will never get better than that.
Fed in 2017 said something along the lines of "a 36 year old winning 3 slams in a year is ridiculous". Why would he say that if he improved and practiced so much?