Doesn't Who's Who's beef with Queen suggest Who's Who should be close to him in combat ability? Their bad blood has been referenced on three separate occasions now, and he's been built up as quite the formidable combatant.
I'm sorry, but I've found Kaido's crew much more impressive than Big Mom's. I would find this argument more convincing if you used Big Mom to make it. I know Kaido's crew should be ~ Big Mom's, but I don't see it. Besides, we know more about Big Mom's crew than Kaido.
Premise 1: DR Santoryu Zoro was on the same level as DR Law.
Premise 2: Asura is a massive power up for Zoro.
Conclusion 1 and Premise 3: DR Zoro was significantly stronger than Law.
Premise 4: Due to the Enma training Zoro grew more than Law since DR.
Conclusion 2: Current Zoro is significantly stronger than Law.