Sardinas has played primarily shortstop since signing with the Rangers -- and current Padres general manager A.J. Preller, who was with Texas at the time -- out of Venezuela in 2009. The 23-year-old can also play second and third base, and he has batted .285 with 107 steals in seven Minor League seasons.
"I don't think we signed him to relegate him to Triple-A the rest of the year," Padres manager Andy Green said. "I think we signed him with the intent of him being one of the names we add to the mix, possibly playing shortstop for us in the future. I don't know when that day is set that he's going to be here."
No position has troubled the Padres more this season than shortstop, where Alexei Ramirez has struggled immensely. The club called up No. 12 prospect Jose Rondon earlier this month, but it would like to get him further seasoning before potentially handing him the keys.
The Padres' Minor League system is stocked with quality shortstop prospects -- including Rondon, Javier Guerra and Luis Urias. But none of that trio is big league ready, and they probably won't be by 2017 -- which could give Sardinas a chance to compete for the starting-shortstop role.
"If he's doing well," Green said, "I'd say he's probably part of our mix going forward."
The Rangers promoted Sardinas in 2014, and he posted his best big league season to date, batting .261 in 43 games. He was dealt to Milwaukee that offseason, and he hasn't batted above .200 since.
To clear room for Sardinas on the 40-man roster, the Padres placed Erik Johnson on the 60-day disabled list. The right-hander, acquired in the James Shields trade, is dealing with a right elbow sprain and won't pitch for the remainder of the season -- though surgery appears unlikely.
AJ Cassavell covers the Padres for MLB.com. Follow him on Twitter @ajcassavell. This story was not subject to the approval of Major League Baseball or its clubs.