Thomas, 28, was hitting .296 with eight doubles, nine home runs and 25 RBIs in 36 games with the Red Wings. He appeared in 12 games with Minnesota last year after being claimed off waivers from the Tigers. He is a career .246 hitter with nine homers in 157 Major League games.
Robertson was the Twins' third-round Draft pick in 2006.
Cash Kruth is a reporter for MLB.com. Follow him on Twitter at @cashkruth. This story was not subject to the approval of Major League Baseball or its clubs.