The Twins finalized a one-year deal with righthander Ramon Ortiz worth $3.1 million on Monday.
Ortiz, who will be 34 on Opening Day, was 11-16 with a 5.57 ERA last season with Washington. He is 79-76 in his eight-year career but has not had a winning season since 2003, when he was 16-13 with the Angels.
His signing gives the Twins a potential starting rotation of lefthander Johan Santana and righthanders Carlos Silva, Boof Bonser, Sidney Ponson and Ortiz. Twins General Manager Terry Ryan said prospects such as Matt Garza, Scott Baker and Glen Perkins still can pitch their way into the Opening Day rotation, but the club needed pitching depth.
"We were awfully young in many spots of the rotation," Ryan said.
To make room on the 40-man roster, the Twins placed outfielder Alex Romero on waivers. Romero, once highly thought of as a prospect, was claimed by Arizona.
Ryan might not be done signing free-agent pitchers. Bruce Chen remains a target, as the Twins would like to bring in another lefthander to compete for a bullpen spot and take some of the workload off Dennys Reyes. Chen, 29, was 0-7 with a 6.93 ERA in 40 games (including 12 starts) last season for Baltimore.
Mike Venafro, Randy Choate and Carmen Cali are among lefthanded relief pitchers being invited to camp.
"I'd like to take care of that lefthanded side," Ryan said.