It was never proven Kaido was the WSC. It was always a rumor. I believe the reason that rumor exist is because of his incredible durable body. His body makes it incredibly difficult for him to be hurt, even harder to scar, and at this time impossible to kill. In my opinion his body makes up at least 60% of his strength. If he didn't have that body Oden would have killed him with one hit.
That brings me to my next point which is Yonko are grossly overrated. It's got to the point where some people believe being a Yonko can't be touch except by another Yonko and a Yonko can easily destroy any none Yonko in an instant.
Oda has made it clear that's not true.
Marco had an even clash with Big Mom. She relied on her oldest son for help against him. She acknowledged she didn't have enough power to spare against Marco. Yamato was able to hold off Kaido alone for a while.
Kaido and Big Mom combination attack Hakai, the strongest attack we have seen in the manga, was temporary blocked by Zoro and failed to defeat him. Zoro with 20 to 30 broken bones and poor condition bested and scared Kaido.
Based off those facts either people need to acknowledge a high/top YC can hold off a Yonko or Zoro is above YC level.
That brings me to my next point which is Yonko are grossly overrated. It's got to the point where some people believe being a Yonko can't be touch except by another Yonko and a Yonko can easily destroy any none Yonko in an instant.
Oda has made it clear that's not true.
Marco had an even clash with Big Mom. She relied on her oldest son for help against him. She acknowledged she didn't have enough power to spare against Marco. Yamato was able to hold off Kaido alone for a while.
Kaido and Big Mom combination attack Hakai, the strongest attack we have seen in the manga, was temporary blocked by Zoro and failed to defeat him. Zoro with 20 to 30 broken bones and poor condition bested and scared Kaido.
Based off those facts either people need to acknowledge a high/top YC can hold off a Yonko or Zoro is above YC level.