Good Son

FRANK SINATRA FAWNED OVER HIM. WARREN ZEVON WROTE A TRIBUTE SONG. Sylvester Stallone produced his life story as a movie of the week. In the 1980s, Ray “Boom Boom” Mancini wasn’t merely the lightweight champ. An adoring public considered him a national hero, the real Rocky.

From the mobbed-up steel city of Youngstown, Ohio, Mancini was cast as the savior of a sport: a righteous kid in a corrupt gam...