I hadn't really thought about it before, but the characters who play in an unsportsman-like way -- Atobe, Akutsu, Kirihara -- all come back later in some way to show us that they've been transformed by that match into someone who doesn't play that way anymore, but only in the anime. Akutsu training Ryoma, Atobe vs Sanada (and also Atobe vs Ryoma at the training camp), Kirihara at junior selection camp. None of that happens in the manga.

So not a sports series.