Frasso (shoulder) was optioned to Triple-A Oklahoma City on Sunday.
Frasso is still recovering from procedures on his shoulder and hip, and he's not expected to be ready to pitch until late in the season. Once healthy, he'll likely return to the mound with Oklahoma City, where he produced a 3.26 ERA and 1.36 WHIP with 13 strikeouts over 19.1 innings in four starts last season.