Knew where the rocks wouldn't fall, knew where his sword was because he looked for it in the future, same SFX. I know this isn't quite like spying on naked women and suddenly using FS, ryuo and CoC at the same time but it's something.
Zoro vs Shiryu is going to be the end of battledome threads.
You might be on to something.
We all know how the power (BOAT) Zoro used to cut Mr 1. The ability to cut steel or not cut paper turn out to be barrier haki. It's irrelevant if Oda originally planned that or not.
It wouldn't surprise me if the power Zoro used to sense the location of his sword and know the rocks wouldn't land on him turned out to be or became CoO (FS) or some other advance CoO.
This is the databook information on Lion Song:
Skill 9:
> One Sword Style Iai ( Re-sheath ) Technique 【Shishi Sonson ( Lion's Song )】:
This is a special iai technique in which all the power is concentrated into a single sword. By sensing the enemy's "breath", it captures the force, speed, and angle of the cut,
it cuts through iron with a lightning-fast sword strike!!
We can see from the databook info Zoro obtains a lot of information from sensing his opponent. If nothing else this should be enough to place Zoro's CoO power/skills at least at an intermediate level.