Treinen (1-1) was tagged with the loss Thursday against the Padres after giving up a run on three hits across one inning.
He pitched the eighth after a strong start from Walker Buehler, but Treinen allowed back-to-back singles to Jurickson Profar and Victor Caratini before the game-winning run crossed the plate on a double play. Treinen was coming off six straight holds and this outing also ended his streak of scoreless appearances at six.