Brock Purdy’s journey to becoming a starting NFL quarterback is one of the most inspiring stories in recent football history.

SANTA CLARA — Brock Purdy did not look stressed. He was sitting in a folding chair at his locker, with Thursday’s practice script in one hand and his right foot propped up against the stall.

Brock Purdy is now the star quarterback of the San Francisco 49ers, fresh off a season in which he led the NFL across the efficiency spectrum and finished as an MVP finalist. Just months from now ...