It is essential to the story because that is where they play baseball. It's important because thats where he faces the main conflict.
Benjie and Josh are trying to make the middle school baseball team but joshes dad wont let him. Throughout the book Josh tryes to talk his dad into letting him play, but he always says no. His dad has bigger plans, he takes him to a higher class baseball team to play on instead. Once he is on the new team he started getting into sterroids, and fights with his teamates. Now he is regretting joining this team and, not thinking it was a good idea.
one main conflict was Drugs, fights, and getting bullied.
yes the conflict is resolved, by luke deciding to quit the team, because he knew that even though they said it was not sterroids, that it was.
he changes physically because of the sterroids but becomes mentally weaker.