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...
There's an old saying, "Chance favors the prepared mind," to which I would add just one word: "somewhat". I think that, in a weird universe where Oarai had been facing another school in the finals than Kuromorimine, one whose tactics and practices Miho didn't know as intimately, the outcome...