Complex sentence: The recovery went well, and by the following summer, he made eight starts for the Gulf Coast Nationals of the Rookie-level Gulf Coast League in 2013 and posted a 2.78 ERA.
Split into simpler sentences: The recovery went well, and by the following summer, he was back on a mound in a game. He made eight starts for the Nationals GCL team in 2013 and posted a 2.78 ERA.