Sampson, a 22-year-old right-hander, is 7-1 with a 2.27 ERA since May 16. Overall, Sampson is 7-4 and has a 2.67 ERA in 16 games (15 starts) with San Antonio. He has 94 strikeouts over 84 1/3 innings with the Missions.
Part of Sampson's success can be attributed to his improved slider, which has become a very good pitch for him this season. He was named the Padres' Minor League Pitcher of the Month for June after going 3-1 with a 2.20 ERA in six games.
Sampson was selected by the Padres in the fourth round of the 2009 First-Year Player Draft.
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.