I'm not sure I understand Okubo's remark. Who is he saying isn't trying to fight for real?
If Misasa is unable to deal with Yumigahama's thrusts and keeps backing away (without properly moving in a circle to not actually get a ring out), then that's that. Misasa wasn't fighting back properly either and was pretty much aiming to get in this position with Yumigahama having his back to the darkness.
So Yumigahama is a martial arts savant, but other martial artists still consider that he's wasting his movements?
Well in any case, we can see that Yumigahama's ego is quite big. He truly believes he was the one who couldn't be seen through by Metsudo and his men, and that he himself can see right through them. It's like he's really setting up flags to be had. But I assume he'll surmount them, and then the fight will go in the nitty gritty and then, someone wins. I would expect Misasa, because the blow on Metsudo if his current fang is worse than one who defected.
In any case, in this chapter, we didn't see anything of what Misasa could do. I mean he can dodge.
@MarbleCitadel
This isn't an enclosed space though. It's a delimited space.
If his skills involve using walls (having it in his back and having the opponent punch into it), or using the objects in his surroundings intelligently to protect himself and attack his opponent, there's not much of that here. They're not allowed to step in the darkness but that's it. I don't really see how he can make use of that, so I'm looking forward to how that element is incorporated. Maybe he really is good against an opponent with his back against the wall?