When has Zoro ever even been on the losing end of a non-major fight, let alone outright lost?
Let's take a look at Zoro's post-TS side-quest fights:
Hody --> Neg diff
Hyouzou --> Neg diff
Monet --> Beyond neg diff
Pica - Mid diff
Killer - Mid diff
Actually, it's not even about that. Zoro doesn't even lose at all, unless you think he's getting a power-up against Lucci.