Six Innings by James Preller

Two best friends...no longer best friends.  Sam is battling cancer and Mike is playing on a baseball team set to win the championship.  Sam used to play on the team but now is the announcer.  Sometimes in life, things get complicated.  Will the game bring them closer together...or push them farther apart?  -Mrs. Ekstrom

Amazon summary: Two teams, six innings, one game.

A lively cast of characters―baseball-loving boys between the ages of eleven to thirteen―are playing the biggest game of their lives. With acrobatic catches, clutch hits, dramatic whiffs, and costly errors, this game is full of action. But as the book unfolds, pitch by pitch, a deeper story emerges, with far more at stake: Sam and Mike, best friends, are trying to come to terms with Sam's newly diagnosed cancer. And this baseball diamond becomes the ultimate testing ground of Sam and Mike's remarkable friendship as they strive to find a way to both come out winners.

This is for the championship.

This is for life.