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

Mr. Goldstein is the former coach of the Latimer Panthers. After suffering a heart-attack, Goldstein stayed with the team as an assistant coach. Described as aged, elderly, and devoutly faithful, he serves as Slam's mentor, challenging him and reminding him that the ability to Slam to do what one loves to do is a gift from God.