The Washington Nationals have signed versatile veteran infielder/outfielder Mark DeRosa to a one year contract, the club announced today. This is a no-brainer: we’ve always been fans of DeRosa, who is a welcome addition to the Nationals’ bench. He can hit and field, is a great presence in the clubhouse, and is a steady veteran of the type that Davey Johnson likes. That said, DeRosa had an up-and-down year in 2011 — though mostly down. He suffered a nasty wrist injury, which limited his season to under 50 games.

The signing of DeRosa, which has been expected, fills one of the team’s identified needs: putting together a bench that surpasses the poorly performing bench of last year. DeRosa is a plus, a kind of Jerry Hairston, Jr. player but with more stuff at the plate coupled with the ability to play any number of positions. Additionally, DeRosa said that he wanted to play for the Nationals after it became clear that his time in San Francisco was up. DeRosa is just three years on from his best years as a player when, after a doubles-heavy tenure with the Rangers, he was signed as a free agent by the Chicago Cubs. In 2008, he hit .285 with 21 home runs.

DeRosa has to show that he’s healthy; in his case, passing a physical is more than just pro forma. DeRosa’s wrist injury last year (on a checked swing, no less), might have ended his career, and some Nats fans are concerned that his wrist is now “shot.” If that’s the case (which will become clear, we assume, in Spring Training), then he might not have the late-inning pop that has become his trademark.

But this is a plus, and a big one. DeRosa could fill a yawning need at first base. Adam LaRoche spent last season injured and Chris Marrero’s torn left hamstring will make him uncertain for Spring Training. Then too, though no one will mention it, Ryan Zimmerman has had problems staying healthy — and the Nationals simply cannot afford another power void season at third base. So, if all goes as unplanned planned, we could be seeing a lot of DeRosa in 2011.