If this series isn't designed to be short and focused on just the first-years going to nationals, Gaku might well become captain eventually. He's clearly the one who has what it takes to be the lynchpin of the team.
Also, a neat aspect of this development is that it was hinted at before, though in a way that only makes sense after the fact: Gaku has, a couple times, said "my hunch was right" during games. So he's already making correct calls of where the ball's gonna land based on his talent for reading people, he just needed to realise what he was doing and now he needs to learn how to deploy that talent effectively. I guess Ja'ichi are gonna regret letting Umino get footage of their practice sessions.
A minor peeve of mine with the translation: I haven't seen the raws, but when Gaku considers Kyougoku's fast reaction, I'd bet the original used どうして or なぜ for the question translated as "Why did Kyougoku-sensei reach for where the ball was going (…)?". But it makes no sense to ask what the reason was in this context: the two Japanese conjunctions are ambiguous, they can mean "why" but also "how". So what Gaku was asking himself was "How did Kyougoku-sensei reach for where the ball was going (…)?"
I know it's a minor thing, but this happens so often in translation, even officials, and it took me years to correct myself when translating, so I thought of pointing it out. Otherwise it was a pretty good translation, I loved "nagging biddy". Keep up the great work and thanks!