I don't think people realize that this means Zoro has a higher attack power than luffy and is faster. Luffy G4 ryuo did nothing to Kaido, Zoro will be fatally wounding and killing Kaido. Zoro onigiri attack had more of an effect on Kaido than G4,Punk Rotten and Room had combined. Even Zoro says he has more he can do, while Luffy went all-out with G4 punch and it resulted in Kaido shrugging his shoulders in pity.
Zoro also blitzed Kaido, while Luffy was blitzed by Kaido. Zoro neg diffed Big Mom's top tier prometheus attack, while Luffy and co were hit by an even smaller prometheus attack.