Well, in the original series, Pravda's victory over Kuromomine occurred because of exactly one thing -- Miho's decision to rescue some of her teammates who were in danger, allowing Katyusha to fire the shot that took out their flag tank. That's great for Miho's story, but it doesn't tell us anything about Katyusha. So this story is focusing on Katyusha's development as a commander, while at the same time relating how things at Kuromomine (and in the sport in general!) got to the point where Miho felt she had to do what she did, acknowledging that Katyusha's victory was ultimately a hollow one. Their win in that tournament isn't a Rocky moment, it's very nearly the nadir of the series' backstory.
In the process, it's contradicting a fair number of other 'prelude' type stories that have been told over the years. That's just what happens when you have a franchise expanded by diverse hands, and there's no real point in crying about it