Scott Williamson, 30, missed a month with elbow trouble earlier this season, and has struggled when he has been healthy. He has a 5.08 ERA over 28.1 innings for the Cubs, including a 10.12 mark since coming off the DL on June 29.
When he is healthy, Williamson is an above-average setup man. The former Rookie of the Year owns a career 3.22 mark and has averaged better than 11 strikeouts per nine innings.
In exchange for the right-hander, the Padres gave up a pair of talented minor leaguers who have been unable to convert their ability into success.
Joel Santo, 22, throws in the mid-90's with ease, but has struggled to control his secondary pitches, leading to a 6-6 mark and 5.38 ERA in his second season in the Midwest League.
Santo's year got off to a rough start when the team felt his work ethic was lacking and left him in the desert out of spring training. When he reported to Fort Wayne, he sulked over being put in the bullpen before finally getting back to the rotation in May. On the year, he has walked 54 while striking out 48 in 92 innings of work.
Fabian Jimenez, 19, has one of the highest ceilings among the pitchers in the Padres' system, but the young lefty from Columbia has struggled with control and consistency. After a devastating 2005 campaign, Jimenez has posted a 4.43 ERA in 17 starts for the Wizards this year, but has walked 52 against 54 strikeouts in 87.1 innings.
It appears Williamson's arrival with the Padres may mark the end of Eric Young's tenure with the club. The 39-year-old utility man is already facing a reduction in his playing time with Terrmel Sledge's addition to the roster and Ben Johnson preparing to come off the disabled list.
Young has hit just .212 in his second season with the Padres and has struggled defensively in left field where he has seen most of his playing time.