On April 28, , Sizemore broke his hand on a play at second base with the San Diego Padres' Gene Richards. The injury sidelined Sizemore until the end of June, and likely played a part in the career low .219 batting average he put up that year. Regardless, the Phillies repeated as division champions, and Sizemore provided the Phillies with one of the few bright spots in their line-up in the 1978 National League Championship Series. The Dodgers once again defeated the Phillies in four games, however, Sizemore batted .385 with a triple, an RBI and three runs scored.