The Giants have designated right-hander Hunter Strickland for assignment, CSNBayArea.com's Andrew Baggarly reports (Twitter link). This creates 40-man roster space for Yusmeiro Petit, as CSN Bay Area's Amy Gutierrez reports (via Twitter) that the Giants have purchased Petit's contract and optioned George Kontos to Triple-A.
Strickland, 24, was originally an 18th-round draft choice of the Red Sox in 2007 and was dealt to the Pirates in 2009 as part of the Adam LaRoche trade package. The Giants claimed Strickland off waivers in April and he'd posted an 0.86 ERA, 9.9 K/9 and 4.6 K/BB ratio over 21 relief innings at High-A ball this season. Strickland has a 3.80 ERA and 3.18 K/BB ratio over 388 career minor league innings.
Petit was outrighted off San Francisco's 40-man roster in March but chose to accept his assignment to Triple-A instead of becoming a free agent. Petit pitched 4 2/3 innings for the Giants last season, his first taste of Major League action since 2009. The right-hander posted 5.57 ERA over 229 1/3 innings for the Marlins and Diamondbacks from 2006-09 and he has a 5.24 ERA over 12 starts for Triple-A Fresno this season.