Olson, 25, enters only his fifth professional season yet has 33 major league starts under his belt the last two years with the Orioles. The southpaw made his big league debut with seven starts for Baltimore in 2007 at the age of 23 and followed up with 26 starts in 2008. Olson went 9-10 with a 6.65 ERA (98 ER/132.2 IP) last year, ranking fourth among American League rookies in starts, fifth in wins and innings pitched and sixth with 83 strikeouts.
The six-foot-one, 204-pound Olson began the 2008 campaign with Triple-A Norfolk and went 1-2 with a 2.97 ERA (12 ER/36.1 IP) in seven starts covering two stints. He struck out 39 batters in 36.1 innings. Olson went 1-1 with a 1.85 ERA (5 ER/24.1 IP) in five April starts to earn a promotion to Baltimore. He also had a stint in Triple-A from August 20-September 1 before being recalled to the Orioles for the rest of the season.
Olson is 12-10 with a 2.96 ERA (126 ER/383.2 IP) in 71 career minor league appearances, 66 as a starter. He has struck out 380 and walked 125 in 383.2 innings, an average of nearly 9.0 strikeouts and 2.9 walks per nine innings. Olson has allowed only 27 home runs in his minor league career, an average of one home run per 14.1 innings.
Originally selected by the Orioles in the sandwich round (48th overall) if the 2005 June Draft, Olson quickly rose through the Orioles system, reaching Double-A Bowie by the end of his second professional season in 2006. He began the 2007 season in Triple-A Norfolk and later made his big league debut that year in his third pro campaign.
Williamson, 23, went 0-1 with three saves and a 3.72 ERA (12 ER/29.0 IP) in 20 relief appearances between Single-A Aberdeen and Single-A Delmarva. The six-foot-five, 233-pound Williamson struck out 42 and walked only five batters in 29.0 innings between the stops, an average of 13.0 strikeouts per nine innings, and limited opponents to a .221 batting average. He was originally selected by the Orioles in the 14th round of the 2007 Draft.
Pie, who turns 24 on February 8, batted .223 (58-for-260) with three home runs and 30 RBI in 130 games for the Cubs the last two seasons. He hit .241 (20-for-83) with one home run and 10 RBI in 43 games with the Cubs last season.