Olsen was selected in the sixth round of the 2002 MLB Draft by the then Florida Marlins. He quickly developed into one of the game’s top young pitchers. Olsen went on to post an ERA of 4.04 over 31 starts spanning 180 2/3 innings in 2006.
The club then traded him to the Washington Nationals along with outfielder Josh Willingham in exchange for Jake Smolinski, P.J. Dean and Emilio Bonifacio.
Olsen, with the Nationals, posted an ERA of 5.76 over 28 appearances, including 26 starts, spanning two seasons. The 28-year-old missed the entire 2011 season due to shoulder issues and made three starts in the Chicago White Sox minor league system last year.