I doubt it as the teacher (director/coach) hit him first in the stomach with a bat during his first year as a pitcher, and then Hiro ended up quitting the team. Also, because this is a Japanese Manga there is the act of saving face. There is no way the coach who pretends to be a badass and gets his ass kicked by a teenager he bullied would ever want his peers to know how pathetic he truly is.
I do love it when someone being bullied takes revenge and shows how pathetic the bully is.