Zoro with current feats is on the same level as G3+ G2 which didn't stand a chance against Doffy.
Law never landed a clean hit on Doffy, he was getting out classed by Doffy through out the entire battle. His raw skills aren't really that great given the fact that he relies to much on his hax. Even something as weak as black night was enough to keep Law busy when Luffy fodderized one while holding off Bellamy. He was getting outclassed even against Vergo. If it isn't for Vergo's ignorance, the story would have been different.
Zoro on the other hand posses better raw skills than Law on top of having nearly as much fire power as Law. Only thing Law has over Zoro as a fighter is his cutting ability which is utterly useless against someone like Doffy when you doesn't posses enough raw skill. Zoro can certainly put up more of a fight against Doffy than Law regardless of how he'd fare against Law.