Hjelle was returned to Triple-A Sacramento after Thursday's doubleheader in Milwaukee, Evan Webeck of The San Jose Mercury News reports.
Hjelle joined the team as the 29th man for the twin bill. After allowing one run in five innings of bulk relief work, he'll return to the minors. The strong outing was only enough to lower his season ERA to 5.73, but his 15:4 K:BB across 11 frames is encouraging.