Tbf tho that same Kaido ended up mollywhopping G5 ACoC Luffy for the entirety of Ch.1047, with an onslaught that would've slaughtered anyone else. Bearing in mind Kizaru could only match an ACoC-less G5 Luffy, even if he wasn't 100% serious.
Kaido vs Base Luffy just strikes me as how Kuri could go from matching base Luffy to outperforming Snakeman.
You can't take Kaido's feats against G5 away, and it's not like he used any power-ups to start bodying G5 either - meaning he was always that strong, he just got more serious. I suppose you can tell how serious he is by the level of his Bagua, and when he's at Death Destroyer he's damn near unmatchable.