Coghlan, 31, has combined to hit .165 (35-for-212) with five home runs and 19 RBI in 78 games this season between Oakland and Chicago. He was placed on the 15-day disabled list on August 17 with a right rib contusion. Coghlan saw action in five rehab games as part of his return, batting .471 (8-for-17) with three doubles and a 1.118 OPS with Iowa.
Coghlan rejoined the Cubs through a trade with Oakland on June 9 after spending the 2014 and 2015 campaigns with the club, batting .265 (219-for-825) with 53 doubles, 11 triples and 25 homers in 273 games with the team. Last season, Coghlan set career marks with 16 homers, 58 walks, 47 extra-base hits and 148 games played as he helped the Cubs to a playoff berth. He was traded from Chicago to Oakland February 25 of this season for right-handed pitcher Aaron Brooks.
Smith, 32, was acquired by the Cubs from the Angels on August 1 and is 1-4 with six holds, six saves and a 4.14 ERA (19 ER/41.1 IP) in 44 relief appearances between the clubs this season. He was placed on the 15-day disabled list on August 17 with a left hamstring strain. He made two rehab outings with Iowa this week, tossing a pair of scoreless innings.
In his career, Smith is 40-27 with a 2.97 ERA (185 ER/560.0 IP) in 629 major league relief appearances covering the last 10 seasons. He has limited foes to a .228 batting average and .308 on-base percentage while allowing only 0.64 home runs per nine innings, contributing to a .331 career slugging percentage against. He has limited right-handed hitters to a career .216 batting average against.
Buchanan, 26, went 12-8 with a 4.34 ERA (68 ER/141.0 IP) in 24 appearances (22 starts) with Iowa this season. He had a strong finish to his Triple-A campaign, going 2-1 with a 1.35 ERA (3 ER/20.0 IP) in his final three starts. Buchanan was in spring training with the Houston Astros but was released on March 31. He signed a minor league deal with the Cubs in early April and joined Iowa on April 18.
The righthander has pitched parts of the last two seasons in the big leagues with the Astros, going 1-3 with a 4.06 ERA (20 ER/44.1 IP) in 22 appearances (20 in relief and two as a starter). He was originally selected by Houston in the eighth round of the 2010 Draft out of North Carolina State University.