What a cruel joke. Since Marineford, we've been pointing out the shortcomings of Kizaru's Devil Fruit abilities, which failed to do anything against pre-timeskip Luffy. Oda is just being consistent here with Franky ~ pre-timeskip Luffy. In fact, since Sabaody, people have been playing blind and making excuses that the admirals were restricted from using everything they had. It's like saying Kaidou needs to use Flaming Bagua, drunken mode, and his strongest attacks to defeat Morley ~ similar to how Franky. Kaidou with just one blow, took down post-Whole Cake Island Luffy, who is far above Morley and Franky.
In his base form, Kaidou won a 1 vs 9 fight with nothing more than casual blows against opponents much stronger than him. The admirals are extremely dependent on their Devil Fruits, and Kizaru has shown 100% of that dependency here. The same goes for Green Bull, who was complaining about not being able to use 100% of his Devil Fruit against Morley, even though he was already using his broccoli form (utilizing his Devil Fruit, so part of his Devil Fruit abilities was already in use). Kizaru's Haki hasn't even been highlighted once in all these chapters, and they are completely different from the monsters known as Yonkou.
Kizaru, Green Bull, perhaps Fujitora, are all physically lacking (Fujitora was being pushed by a flying bar from Zoro in Dressrosa and by Luffy's G3 attacks)...
People think that Aokiji and Akainu were the two physically strongest in the Marines, but in reality, they were visibly embarrassed when witnessing Prime Aokiji having to use his Devil Fruit powers just to try to match the physical strength of an old Garp. Emphasize the word "old" here – imagine a Prime Garp.
I would put a trash can on my head if all of Prime Kaidou's physical strength was enough to match the physical strength of an Old Garp, who admitted a thousand times throughout the manga to be weaker than his Prime version.