Whitebeard was definitely above Oden dude... Did you see that Roger and Whitebeard clash... Even Oden was acting like fodder commenting on the sheer power involved
I mean even if he trained to get stronger, whitebeard was already way ahead and could still also be getting stronget
The more likely thing is that Kaido wasn't as strong as we thought he was
That clash is not even impressive and that was a weaker Kaido than now
Also Oden has more bandages and damage vs Kaido than he had vs Roger pirates after 3 days.
Oden was commenting on their haki no Power overall.
The fact WB didnt avenge Oden nor take down this version of Kaido and his empire just tells me
Rock pirates dont like fighting each other for the sake of it, and WB/BM werent that much strong
This is basically Kaido pre Yonko status, pre WSC and 1 vs 1 hype.
Yet WB BM Navy coulnt keep this chained or take him out totally as how Teach took out WB pirates totally.