1) Jacare vs. Mousasi #1 was 10 years ago and ended with an upkick. I'm not saying an upkick doesn't take skill, but we really don't know who the overall better fighter was based on that. The same could be said for Oleg vs. Renzo 10 years earlier.
2) Jacare beat Mousasi decisively everywhere in the rematch. You can throw in PED allegations if you want, but Jacare has never tested positive. For all we know, Mousasi has done as many or more PEDs than Jacare.
3) Mousasi himself said he's sparred Lima and noted there's a significant size difference between him and most WWs. Rory is an inch shorter than Lima and has roughly the same build.
As for Mousasi looking better and better, I'm not convinced. He certainly didn't against Shlemenko, a pudgy MW who could easily fight at WW. And if we want to use the "he lost, but that fight woke him up" excuse, I could say the same for Weidman, who looked 10X better in his next fight with Gastelum than he did vs. Mousasi.