That season 1 was about Kageyama's character development ans season 2 is gonna be about Tsukishima's character development.

Like think about it? Why do you think Karasuno has 2 messed up characters? No offense

Kageyama learned to trust his teammates once again in SEASON 1

And Tsukishima is going to learn how to #&^38@*&39@*@:#@*@ (not gonna place spoilers for anime watchers but manga readers, you know what I mean) in SEASON 2