Law's fruit is hax but combat wise Law is weak. Smoker pressured Law in sheer combat. Base Doffy heavily pressured Law in close combat too, without much effort, with his agility allowing him to avoid Law's attacks. Law couldn't even overpower Doffy's clone outside the room. vs Hawkins, it also was a toe to toe.
Zoro's speed feats are insane - cutting Prometheus when Big Mom tried to attack Luffy point blank, interfering with Hakai when the others were too slow to even react and Killer already accepted death - his attack power, defense and Hakis are ridiculous too.
Law's DF is hax but for someone of Zoro's caliber it doesn't really matter. What is Law going to do? Cut him with spatial hax? Zoro will easily avoid that with his powerful Hakis and reaction. Gamma Knife? Law had to play dead to lay it on Doffy. Zoro will rip his arms off. Heart removal, personality switch, teleporting Zoro? Zoro probably won't even be affected due to his powerful Haki.