Safe at Home
I would say that Nicks antagonist could be himself or baseball. Nick is really struggling with himself and moving up to the varsity team. He is trying to hard to prove himself to the team, and he will not just play the game. Therefore, baseball could be the conflict. Protagonist would be Nick, the main character with the problem. Nick is trying to get his coach to send him back to JV, but the coach is making him work hard, and helping him after practice so have that spot. Nick needs to stop fighting himself and play the game.