@Doffy.:
Yes but we barely know anything about Wano and it's people . Saying that Mihawk is automatically stronger than the leader of Wano whom hasn't even been mentioned once , simply because Mihawk has the title is such a ridiculous claim.
Saying that someone who hasn't claimed the title, of a position that it's main component is ambition, it's a very dubious claim.
In the real world, who knows, but the narrator, ODA said that Mihawk was the strongest. If there's someone better, that one isn't ready for the top.
Yes, there's always someone better, but I'd place my money in some random girl from the south blue than in the king of wano.
–- Update From New Post Merge ---
There isn't a league of bestest swordsman, where they clash all year around, and the finals are in the great kendo stadium of marijoa, there's the strongest, and if you beat him, then you are the strongest, as simple as that.
As this is One Piece, and Oda said that Mihawk was the strongest, and what point would it be for zoro to go "Oh, yeah, he was stronger than mihawk, now I know that I can beat him!"