None of them( Whitebeard, Kaido and Big mom) were top tiers at God Valley. They were all Yonko commander level.
Because of what?
Whitebeard and Big mom aren't back then YC or even above? Sry but do you want to tell me that Whitebeard and Big mom in same years as Smoothie and Jack aren't yonkou commander lvl?!!
The first false logic which you and JoNudle make is to compare fucking Yonkous with YC. That is false, Big mom and the other Yonkous have far far more potential then Smoothie and the others. They beeing in that age above Smoothie and co make total sense. After all the different between YC and Yonkou are to large.
No way that Big mom and Whitebeard in same ages as Jack and Smoothie are weaker then them. In the end they are the yonkous at not Smoothie and Jack.
Yes Sengoku said that Big mom and Kaido get far stronger. But the context is here important, he could mean not only their own strenght but overall they gain a new power with a strong crew.
Big mom and Whitebeard beeing back then low top tiers make total sense.