Oda is really settling Zoro and Sanji to be the strongests in this raid.
After the feats Zorogot in the rooftop, he stills struggling a lot against King, and not the "Zoro one shot Calamities" Zorotards claimed.
Thats Oda saying "Don't understimate Kaido's main Commanders"
Everyone in Onigashima knows how much of a big deal is defeating King and Queen, Zoro and Sanji will come at the top by the end of this arc. Dude these are 1.390 Billion and 1.320 Billion bounty dudes.