Vizcaino, 21, entered the 2012 season as the second-best prospect in the Braves organization as ranked by Baseball America and the 40th-best overall prospect in all of baseball by the publication. He is a career 19-15 with a 2.91 ERA (87 ER/268.2 IP) in 65 career minor league appearances, including 50 starts, in four professional campaigns. Vizcaino has 279 strikeouts and only 68 walks in 268.2 innings in the minors, an average of 9.3 strikeouts and 2.3 walks per nine innings. He had Tommy John surgery during spring training and will miss the 2012 season, but is expected to be ready for 2013 spring training.
The righthander made his big league debut with the Braves last season at the age of 20 and went 1-1 with a 4.67 ERA (9 ER/17.1 IP) in 17 relief outings, fanning 17. Vizcaino allowed five runs in one outing covering 0.1 innings and pitched to a 2.08 ERA (4 ER/17.0 IP) in his remaining 16 outings.
Vizcaino began the 2011 season at Single-A Lynchburg and advanced through every level of the Braves system before making his big league debut on August 10. The six-foot, 190 pounder combined to go 5-5 with a 3.06 ERA (33 ER/97.0 IP) in 26 appearances (17 starts) at the minor league level in 2011.
Originally signed by the Yankees as a non-drafted free agent on July 2, 2007, Vizcaino was acquired by the Braves as part of a five-player trade on December 22, 2009. He is a native of Yaguate, Dominican Republic.
Chapman, 25, is 3-6 with seven saves and a 3.52 ERA (21 ER/53.2 IP) in 40 relief appearances for Triple-A Gwinnett this season. He has struck out 60 batters and allowed only three home runs in 53.2 innings while limiting opponents to a .232 batting average, including a .173 batting average by right-handed hitters.
Originally selected by the Braves in the 16th round of the 2005 Draft, Chapman is 17-22 with 28 saves and a 3.93 ERA (162 ER/371.0 IP) in 248 minor league appearances, including eight starts.
Maholm, 30, is 9-6 with a 3.74 ERA (50 ER/120.1 IP) in 21 appearances (20 starts) with the Cubs this season. He signed a one-year deal (with a club option for 2013) with the Cubs on January 10, 2012.
Johnson, 35, is batting .302 (51-for-169) with nine doubles, three home runs and 16 RBI in 76 games for the Cubs this season. He signed a one-year deal with the club January 3, 2012.