The Twins have been searching for experienced arms to boost their starting rotation, and on Tuesday they added at least one well-known pitcher to compete for a starting spot in Sidney Ponson. Ponson, 30, was one of two pitchers that the Twins signed to Minor League deals with invitations to Spring Training. The team also inked right-handed pitcher Brad Voyles, who spent last season with the Cardinals' Triple-A affiliate in Memphis. A career 80-96 pitcher, Ponson went 4-5 with a 6.25 ERA in 2006 during stints with the Cardinals and the Yankees, both of which released him during the year. Ponson has also seen his ERA rise over each of the last three seasons after going 17-12 with a 3.75 ERA with Baltimore and San Francisco in 2003.