The Giants optioned Winn to Triple-A Sacramento on Tuesday, Alex Pavlovic of NBC Sports Bay Area reports.
Winn was added to the 40-man roster in November so that he could be protected from the Rule 5 Draft, but he never stood much of a chance to make the Opening Day squad out of camp this spring. The 25-year-old posted a 4.08 ERA in 108 innings last season between Low-A, High-A and Double-A ball.