So I was watching an analysis of the Punk Hazard arc the other day, and the person brought up an extremely good point. Zoro essentially became what he was dead set against as a kid, and that is like his sensei, looks down upon women. This is prevalent in his interactions with Tashigi, but is shown in full force in his fight against Monet.
If he'd had taken his fight serious with Monet, he would have put her down like he normally would, had it been any male opponent, and dumb luck wouldn't have been what saved the Straw hats and everyone else on Punk Hazard. Had Caesar never had stabbed the heart which he thought was Smokers, Monet would have succeeded in blowing up Punk Hazard, and would have killed everyone on there.
This was a huge failure on Zoro's part. But the guy did bring up another good point, that this is actually a character arc for Zoro, and he'll eventually start to shift back into the mindset that he had as a child.