Complex sentence: Sullivan hailed from Alabama and seemed an unreconstructed Southerner, despite all his years in New England; he had made his career with the Red Sox toadying up to Mrs. Yawkey, becoming something akin to an adopted son to the childless couple.
Split into simpler sentences: Sullivan hailed from Alabama and seemed an unreconstructed Southerner despite all his years in New England. He had made his career with the Red Sox by good relations with Mrs. Yawkey, becoming something akin to an adopted son to the childless couple.