Gerber (forearm) began a rehab assignment with the Mariners' rookie-level Arizona Complex League affiliate over the weekend and gave up an unearned run on two hits over one inning in his first appearance Saturday.
Gerber has resided on Triple-A Tacoma's injured list all season after straining his right forearm in spring training. The 25-year-old still possesses a spot on the Mariners' 40-man roster, so he could be in the mix for a call-up to the big club once he completes his rehab assignment and proves his health at Tacoma.