1. Learn what one shot means. It's not a one shot because they were fighting and hitting each other for like 5 chapters.
2. If cover story says anything it's that Jyabura > Kaku
Jyabura was knocked out cold same way Lucci was (in their zoan forms)
while Kaku was fine after Zoro, and even had time for a chit chat and laughter:
If this suggests anything is that Jyabura had way better devil fruit mastery over Kaku because he recovered faster, thus making him stronger than Kaku. That 20 doriki shit looks absolutely worthless now and scales tip to Jyabura's favor.