THE NARRATIVE ARTS : DIAMONDS ARE TRUMPS <i> By Marty Slattery (St. Lukes Press: $16.95; 264 pp.) </i>

Baseball is Bill Mahoney’s curse and his salvation. A one-time San Fernando Valley high school pitching phenom, he is forced out of the game by arm trouble. Then life throws him a dismaying assortment of curves and hard stuff: a brother killed in Korea, a harshly critical father, dead-end jobs, divorce, booze, pills and finally a few innings in a mental hospital.

When Marty Slattery’s novel picks him up, Mahoney is toiling in the bullpen for the Dodgers’ Class A farm team in Lodi, trying to hide his age (39) and the pain of the bone chips grinding in his elbow on every pitch.

It’s “The Natural” all over again, minus the Malamudian metaphysics. Slattery, who has obviously been there, specializes in Valley memories of the 1940s and ‘50s and ballplayers’ ribald chatter on the field and in dugouts, buses and motel rooms. Surprises are few, but cliches don’t hurt too much in a baseball book, because the whole point of the game (and its literature) is that nothing ever really changes.