I guess but Itachi saved his brother from life and death. Sae just came back and became an ass to his brother without really explaining why he changed position, even though he knew his brother looked up to him and wanted to become striker together. Not saying it all Sae fault, I do think Rin could have tried and understand his brother's view and maybe became a team in their new positions. Intead they said some harsh words, that shouldn't be said between family members.
But as a reader I think it gave us more depth and made Rin join BlueLock. Which than helped our main characters grow.
(Just my opinion ╮( ̄▽ ̄)╭)
what the fuck sae just ditched his own flesh and blood..... FOR FOOTBALL??? JUST LIKE THAT??? thats just weird, man