Koss (wrist) went 2-for-3 with an RBI in the ACL Giants' 9-1 win over the ACL Padres in the rookie-level Arizona Complex League on Wednesday.
After being optioned to Triple-A Sacramento on May 15, Koss fractured his left wrist and landed on the injured list. However, he began a rehab assignment in Arizona on Wednesday, logging two singles and an RBI over the first two innings before being lifted in the sixth. The 28-year-old infielder made San Francisco's Opening Day roster but slashed just .071/.133/.143 with a run scored in 15 plate appearances before being sent down.