Keller (1-4) took the loss against the Giants on Tuesday, giving up five earned runs on nine hits over five innings, striking out seven and walking none as the Pirates fell 5-4.
Keller made his return after a knock to the wrist pushed his start back, but it didn't go well, with the Giants jumping on him for three earned in the first inning before added two more in the fifth and chasing him after 93 pitches. He's only thrown 38 big-league innings this season, but the results haven't been pretty, with Keller sporting a bloated 8.29 ERA and 1.87 WHIP in his nine starts.