Prior to Friday's start, Giolito had been serviceable in three outings for Harrisburg. The 21-year-old entered the game with an 0-1 record and a 5.94 ERA, but left with a .500 mark and a much lower 4.18 ERA.
He missed the first month of the season while in extended Spring Training, but was efficient at Class A Advanced Potomac. The 2012 first-rounder went 3-5 with a 2.71 ERA in 13 appearances for the P-Nats before getting promoted in late July.
Alex M. Smith is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.