Complex sentence: In, he served one season the Yankees'MLB pitching coach, Casey Stengel's final campaign as the club's manager, which produced an American League pennant but a defeat at the hands of the Pittsburgh Pirates in the World Series.
Split into simpler sentences: In, he served one season the Yankees'MLB pitching coach during Casey Stengel's final campaign as the club's manager. That year produced an American League pennant for the Yankees, but a defeat at the hands of the Pittsburgh Pirates in the World Series.