Jane Leavy, author of last yearís smash hit, “Koufax,” is on a roll. Not only is “Koufax” due out in paperback this September, but Perennial (a division of Harper Collins) has issued a paperback edition of her 1990 comic novel, “Squeeze Play.” The novel follows the adventures of a woman sportswriter, A.B. Berkowitz, who happens to cover the worst team in baseball. The New York Times Book Review noted that the novel, “does baseball mythology proud