Seth is a quiet, self-doubting teenager growing up in the San Francisco Bay Area. Having lost his father at a young age, he feels a significant void in his life until he discovers a passion for baseball. Though he lacks natural athletic brilliance, he is incredibly hardworking and dedicated to maximizing his abilities. He is deeply loyal to his friends and family, often relying on his mother's guidance when faced with peer pressure.

Jimmy is a highly talented, brash baseball prodigy who introduces Seth to the intricacies of the sport. He is intensely driven to succeed on the diamond, pushed relentlessly by a hyper-critical father who failed to reach the major leagues. While he is a natural leader capable of inspiring his teammates, Jimmy struggles with anger, rebellion, and an increasing reliance on alcohol to cope with his stressful home life.

Seth's unnamed mother is a strong, dedicated single parent who sacrifices her personal life to provide stability for her son. She actively supports Seth's interests, spending her evenings throwing baseball grounders to him so he can practice. Observant and insightful, she sets clear boundaries regarding alcohol and unsafe situations, offering authoritative guidance when Seth faces difficult choices.

Jimmy's loud, hyper-critical father aggressively pushes his son to achieve the major league dreams he himself failed to realize. He demands absolute perfection on the baseball field and frequently belittles Jimmy. His escalating struggle with alcoholism causes severe friction in his family and makes him a volatile, unpredictable presence in the boys' lives.

Todd is a naturally gifted upper-middle-class athlete who initially clashes with his coaches due to his poor work ethic and passive-aggressive attitude. Because his parents largely ignore him, Todd hosts unsupervised gatherings in his well-equipped bedroom and introduces his teammates to drinking beer. He eventually forms a formidable offensive duo with Jimmy on the baseball team.

Rick Sharront is an energetic former professional baseball player who coaches the high school teams. He loves the game deeply and holds his players to rigorous physical and moral standards, frequently running alongside them during conditioning drills. He serves as a fair, upright male role model who readily disciplines players when they break team rules.

Seth's deceased father was an avid golfer whose sudden passing leaves a profound emotional void in Seth's life. Though absent, his memory influences Seth's understanding of dedication; his philosophy about practicing relentlessly to be the "best lousy golfer" inspires Seth to maximize his own limited baseball talents.

Jimmy's mother struggles to protect her son from her husband's volatile, alcohol-fueled outbursts. She briefly relocates to seek safety away from him, attempting to provide Jimmy with a stable environment while navigating the stress of her husband's addiction.

An older teenager who attempts to expose Seth and Jimmy to cigarettes, beer, and pornographic magazines in a secluded cabin. He represents a dangerous, corrupting influence that forces the younger boys to make a choice about their boundaries.

A well-meaning but relatively inexperienced baseball coach who manages Seth and Jimmy's youth team. He struggles to control practices when Jimmy constantly interrupts to explain how his father would run things.

A phenomenal youth pitcher whose dominant fastball deeply shakes Seth's early self-confidence. He develops into a top-tier high school pitcher who serves as a recurring athletic obstacle for Seth and Jimmy.

A young baseball player whose knee is severely injured during a rough play on the field involving Jimmy. His injury haunts Seth, who fears the incident permanently ended Brad's ability to play the sport.

A sophomore pitcher on the Woodside high school baseball team. He occasionally struggles with accuracy on the mound and becomes involved in the team's social drinking scene alongside Jimmy.

A mature, solemn woman who becomes involved with Mr. Winter. Her steady, stately demeanor stands in stark contrast to the younger girlfriends Mr. Winter previously pursued, and she provides a sobering influence in his life.

The owner of the local batting cages who appreciates Seth's dedication to baseball. He enjoys the sounds of the game and provides a space where the boys test their physical limits against high-speed pitching machines.