As a sophomore, Ball played under first-year head coach Stephan Gilling and with brother LiAngelo Ball and cousin Andre Ball. By December 2016, Ball was averaging more than 30 points per game. In late December, he made a half-court shot two seconds into a game versus Crespi Carmelite High School. The shot received widespread media coverage, including from ESPN, CBS Sports, and Sports Illustrated, and drew praise from NBA player Stephen Curry. Ball lost his first high school game on February 5, 2017, when Oak Hill Academy ended his team's 60-game winning streak. In his subsequent game two days later, Ball made headlines nationally by scoring 92 points in a 146–123 victory over Los Osos High School. It was the second-highest individual scoring performance in California high school basketball history. Ball was criticized for cherry picking, as he often waited near half court to get an open shot on his next possession instead of trying to prevent the opponent from scoring. In his sophomore season, he averaged 26. 7 points and almost 10 assists per game, earning MaxPreps Sophomore All-American Team recognition. On July 27, he competed in a highly anticipated AAU game with his team Big Ballers, facing top recruit Zion Williamson and SC Supreme at the Adidas Summer Championships in Las Vegas. Ball scored 31 points, shooting 10-of-27 from the field. According to Adidas, up to 4,000 people, including several NBA players, were in attendance.