If not for one unforgettable fastball, hurled Oct. 3, 1951, pitcher Ralph Branca of the Brooklyn Dodgers might have faded from baseball memory. In a dozen big-league seasons, he won 88 games and lost 68, a workmanlike record, a ticket to obscurity. But for an autumn afternoon long ago. Facing the New York Giants with a 4-2 lead and the National League championship at stake, he threw a high fastball in the ninth inning to the Giants’ Bobby Thomson, a dangerous hitter.