Plot armor, let's goooo! I’m okay with Aoba winning, but I can’t shake the feeling that the writing was less consistent during the final part of the tournament.
Two months ago, during the preliminaries, Aoba couldn’t submit Hazuru due to physical exhaustion. Here, it’s emphasized multiple times how exhausted Aoba is, which is understandable after two grueling matches and the body shots he took at the end of Round 1.
Yet, he first manages to pull off a backpedal combined with some sick defense moves. And then miraculously gets a complex submission (after being knocked down) against a much fresher and physically stronger opponent. In other words, his fighting skills seems to improve with exhaustion and received damage, which feels counterintuitive and more like plot armor to me.
What the author could have done better? I’d say don't let Hachiya's second opponent forfeit. That guy looked pretty big on the poster and could have given Hachiya some trouble. Maybe their fight was planned initially but then was scrapped to increase the pace.
Also, make a longer interval between preliminaries and main tournament (like 6 month), because Aoba's progress in physique and especially stamina is too OP for a person who never did any sports/physically demanding job before and has asthma.