The Giants designated Long for assignment Wednesday, Susan Slusser of the San Francisco Chronicle reports.
The left-handed pitcher was removed from the 40-man roster to make room for outfielder Cal Stevenson, whom the Giants acquired in a trade with the Athletics. If Long goes unclaimed off waivers, he'll likely report back to Triple-A Sacramento, where he's struggled to a 9.90 ERA and 1.90 WHIP over 10 innings this season.