The Minnesota Twins signed right-hander Rich Harden to a minor league contract Friday with an invitation to compete for a spot on the staff in spring training. The 31-year-old Harden sat out the 2012 season after surgery on Jan. 31 to repair the rotator cuff in his throwing shoulder, his latest setback in a long line of arm problems. Harden has the third-best strikeouts-per-nine-innings ratio in the majors since his debut with Oakland in 2003, behind only Tim Lincecum and Clayton Kershaw.