First, why are you comparing pre PU Zoro to post PU Luffy by posting those panels?
Second, it is simple deduction leading to a valid conclusion.
Luffy before PU was getting low diffed by Kaido in all stats. Be could not damage Kaido, could barely dodge his attacks and when he went 1v1 against Kaido, he got knocked out in two moves.
Luffy after PU was able to fight Kaido fat better than before.
So from the above, we saw Zoro before PU fight Kaido as well. He actually did better than Luffy. So from the simple fact that after PU, Luffy was able to go toe to toe with Kaido, it can be validly concluded that Zoro can as well because Zoro got the same PU as Luffy...Conquerors Coating.