The lefty enjoyed a breakout 2005 season in which he went 4-0 with a 1.94 ERA (13 ER/60.1 IP) in 69 relief outings, holding the opponent scoreless on 58 occasions. He averaged 8.7 strikeouts per 9.0 innings that season and was 2-0 with a 0.70 ERA (2 ER/25.2 IP) after the All-Star break. In the postseason, Cotts was 1-0 with a 0.00 ERA (0 ER/2.1 IP) with two holds in six appearances. He earned the win in the second game of the World Series against Houston, retiring the only batter he faced (Mike Lamb).
Cotts, who was originally selected in the second round by Oakland in the 2001 First-Year Player Draft, is 10-7 with a 4.52 ERA (97 ER/193.0 IP) in 199 career games (five starts). He made his Major League debut with the White Sox in 2003, making four starts that season.
Aardsma, 24, posted a 3-0 record with a 4.08 ERA (24 ER/53.0 IP) in 45 relief appearances for the Cubs last season. The right-hander also pitched with San Francisco in 2004, and owns a 4-0 career record with a 4.52 ERA (32 ER/63.2 IP).
Vasquez, a 23-year-old left-handed pitcher, was signed as a non-drafted free agent by the Cubs in 2000. He has spent his entire career within the Cubs organization, most recently going 6-5 with three saves and a 2.75 ERA (26 ER/85.0 IP) in 54 relief appearances between Single-A Daytona and Double-A West Tenn in 2006.
This marks the first trade between the two Chicago franchises since the Cubs acquired pitcher Matt Karchner in exchange for minor league pitcher Jon Garland on July 29, 1998.