Stammen (3-2) took the loss in Sunday's 3-1 defeat at the hands of the Rockies, allowing one run on two hits in 1.1 innings.
Manager Jayce Tingler was forced to deploy his bullpen early following starter Ryan Weathers' injury, making Stammen the third of six San Diego relievers. The righty came in for the sixth and stayed for the seventh but was removed following a Chris Owings solo home run with one out. It was Stammen's second appearance of more than one inning in his last 14 games. He enters the All-Star break with a 2.89 ERA, 1.00 WHIP and 52:7 K:BB Ratio.