I'm not rating them, but...
Nadal:
AO: 19
RG: (20? really?) I don't know, tbh. I tend to think he got pretty lucky in 2019, so I'll go with that one.
WIM: 11. I know he got bagelled in 2006, but he fought back admirably. This was a straight set beatdown in all but name.
US: I'd go 17 just because he never had to get out of first gear. 2011 the only other real contender in which he was, indeed, pretty bad.
Djokovic:
AO: 20, though all those Murray ones tend to blur together.
RG: 20, probably, yes, but I don't think 2012 is far off. If the weather never turns he doesn't make it look respectable. The way he coughed it up on the Monday was terrible.
WIM: 13
US: 2021. 12 and 16 not great either, but has to be this one.
Federer:
AO: 2006? 2009? Probably 06, I guess.
RG: 08
WIM: Argh... 15 or 19. 2019 had higher heights, but the choke job in those first two breakers is monstrous. 2015 he also went walkabout, but it was never there for the taking to begin with.
US: 15. Sure. His relatives calling all of the lines was hilarious. (Asderaki GOAT). 2005 always seemed pretty pathetic to me too.