He wasn't ever beating Nadal at RG when he couldn't even do it when fully in his prime and at his peak years earlier, not even vs an 18 year old Nadal, so how is he now going to do it probably past his prime altogether. No matter what opportunities he took early in the match Nadal would have found a way to win.
2011 U.S Open? Maybe but again he would have had to beat Nadal even if he finished off Djokovic, and he was on the firm losing side of their rivalry, especialy in slams, at that point.
2014 Wimbledon? I am not sure, I saw the match and Djokovic should have finished it off in 4 sets and it is not like Federer choked at the end of the 5th set either. I think Djokovic was the better player that day, and Federer had to be in better form overall to have won that match as opposed to not choking.
2015 U.S Open agreed, he had many chances in that match.
2018 Wimbledon, dunno, I think if he lost to Anderson he was not going to beat a resurgent Djokovic here. I don't think his form in 2018 was up to winning slams anyway, Australia was a super weak event/draw.
2019 Wimbledon agreed 100%