WASHINGTON -- The Nationals continue to stay busy this offseason, as they have reached an agreement to trade second baseman Emilio Bonifacio, right-hander P.J. Dean and infielder Jake Smolinski to the Marlins for left-hander Scott Olsen and outfielder/catcher Josh Willingham, according to an industry source.

Olsen and Willingham -- both of whom are arbitration-eligible -- are expected to fly to Washington to be introduced to the media as early as Tuesday. The Nationals did not confirm the trade on Monday night.

Olsen is expected to be part of a Nationals rotation that finished with a 4.97 ERA this past season. The left-hander went 8-11 with a 4.20 ERA in 33 starts in 2008 and threw a career-high 201 2/3 innings.

How Willingham -- who appeared in 102 games in 2008 and hit .254 with 15 home runs and 51 RBIs -- will fit in with the Nationals is not known. He is a corner outfielder, and the Nationals already have Austin Kearns, Elijah Dukes and Lastings Milledge at those positions. Willingham also can play behind the plate, but that position belongs to Jesus Flores. In addition, he can play first base, but it is doubtful that he'll be a regular there.

Bonifacio was slated to be the Nationals' leadoff hitter and everyday second baseman, but Anderson Hernandez gave a better impression at the position during the final two months of the season, hitting .333 with 17 RBIs. The switch-hitting Bonifacio, who was acquired from the Diamondbacks last July for reliever Jon Rauch, hit .243 with 14 RBIs and was an automatic out from the right side of the plate.

Dean, 22, pitched for Class A Vermont, going 4-1 with a 1.57 ERA in 10 starts.

Smolinski, 19, played for the Gulf Coast Nationals, Vermont and Class A Hagerstown, and hit .271 with four home runs and 33 RBIs.