Old Garp >~ Old Ray
Garp has gotten older, Ray is not as active as Garp so he might be slightly weaker
This isn't a reasonable argument.
The only trio that Oda try to wank every time he has the possibility is Roger, WB and Garp.
No Sengoku, no Ray, no Shiki, no Oden no others legends.
Ray was ofc a top tier character, probably as strong as top Yonko and Admirals, but not close to Roger.
The most probably scenario was/is:
WB=Roger>=Garp
> (high diff) Prime Sengoku >= Prime Ray = Shanks/Mihawk/Kaido/Akainu ecc
Roger is the pinnacle of the strenght in OP as far as we know. And Garp was one of the only two characters who had the strenght to almost kill him.
Now that Ray is not as active as Garp, like Sengoku, the gap is even more huge than before.
Garp is more near to Yonko and Admirals than to Old Ray.