Getting back up and fighting right away indeed means he didn't beat him, lol.
Only the weak ones send people flying because they aren't dealing enough damaji.
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Yes, he heavily outclassed him. Hardening Santoryu is just 3.3% of Zoro's power, while Nika is Luffy's peak.
One hit in Santoryu>>>3 hits in God Mode. I know it is not easy to process how much stronger Zoro is, but Oda's choice.