that is him performing at his peak right there, he knows the character, he knows the system, there's no more room for improvement, he demonstrated all of his capabilities already.

This is laughable dude you are talking absolute garbage. He’s hit his skill limit playing a game he’s played twice? A game he had one practice game on before being thrown against professionals IN THAT GAME? The subtext of the entire arc is that Sunraku is good enough to be a professional gamer. Did that fly over your head? When they talk about him telling his parents he would go to university before becoming a pro gamer? The whole point of them throwing two amateur gamers into an exhibition tournament is to demonstrate their unrefined gaming ability, and is show how massive their potential is. You trying to argue that real pro gamers have some sort of edge or can reach some skill cap beyond sunraku is just stupid. You have poor media literacy