Who is Mr. Goldstein from Slam! and what is their importance?

The former coach of the Latimer Panthers, Goldstein is an assistant coach now following a heart-attack. Aged, elderly, and devoutly faithful, Goldstein mentors and challenges Slam to do better throughout the novel, saying that to be able to do what one loves to do is a gift from God. Goldstein is able to finally get Slam to commit to being a better person and to see that his future is wide open.