I made a mistake, that should have said it was not a surprise attack from killer.
I still believe we can use thes battles to scale their strength. We just have to look at everything we know about them.
Apoo uses two different finding styles. His music fu for his offensive attacks and tonfas for defense. Up until now, Drake has not been able to get a solid attack in. But at the same time we haven't seen Apoo hit Drake once with his tonfas. Every time they fight Apoo seems to be only blocking. That tells me Apoo cqc skills are limited to defense. They are still strong.
Here's comes Zoro who blitz him, cut through his tonfa and cut him down with one attack with one sword. Before this chapter, Apoo was able to either block or evade attacks from Zoro and Drake, even at the same time. This tells me the current level Zoro is now fighting at is too much for Apoo. Meaning, he's much stronger than Apoo.