Gillaspie was a former fast-rising prospect and 37th overall selection in 2008, who played in the major leagues less than 100 days after he was selected. He has spent most of his time in the minor leagues since then, though, batting .287 with 37 home runs and 259 RBIs over five seasons.
Over 29 major league games spanning three seasons with the Giants he hit .205 with one home run and four RBIs.
"He conceivably fits in nicely on the roster, which we’ll obviously decide more about toward the end of next month," general manager Rick Hahn said. "But we see him having a solid hit tool, above-average awareness of the strike zone, solid defensively. He gives us a little versatility in his ability to play third base as well as first. He gives (manager) Robin (Ventura) some options potentially."
Gillaspie, 25, also was appealing to the White Sox because of his ability to hit left-handed. The White Sox have just two projected starters who bat from the left side: Adam Dunn and Alejandro De Aza.
With Jeff Keppinger set to open the season at third base for the White Sox, Gillaspie figures to battle Brent Morel for a backup infield job.
Gillaspie is out of minor league options, which means that if he doesn't make the White Sox out of spring training he would have to go through the waivers process.
"He’s been on our list for a while," Hahn said. "It became a little more apparent over the offseason, he was obviously blocked there by (Pablo) Sandoval and some other infield signings and acquisitions they made. The last few weeks it became a little more apparent there was a chance to get him.
"It was important for us to get him now and have him in camp with us for four-plus weeks and get to know him and how he fits. It’s one thing to see him on video and see the scouting reports and talk to people who know him, it’s another thing to have him in the clubhouse and see how all the pieces fit together. So we wanted to have him sooner rather than later."
Soptic is a hard-throwing right-hander, who had 36 strikeouts in 27 relief appearances with Single-A Kannapolis last season. He was a third-round selection by the White Sox in the 2011 draft.
To make room for Gillaspie on the White Sox's 40-man roster, first baseman Lars Anderson was designated for assignment. Anderson was claimed from the Arizona Diamondbacks on Feb. 1.