The 25-year-old Zastryzny joins the Cubs for the second time this season as he made one appearance during a brief stint with the club in May (4.0 IP, 3 ER). He is 1-2 with one save and a 6.67 ERA (20 ER/27.0 IP) in 10 appearances, three as a starter, with Iowa this season. Zastryzny spent two months on the disabled list due to a lat injury and has made two starts with Iowa since being activated on July 25. He made his big league debut with the Cubs last season, going 1-0 with a 1.13 ERA (2 ER/16.0 IP) in eight appearances, one as a starter. He struck out 17 batters in the 16.0 innings pitched while limiting opponents to a .207 batting average and posting a 1.06 WHIP.
The 6-foot-3, 205-pound Zastryzny was originally selected by the Cubs in the second round of the 2013 Draft out of the University of Missouri. He is 18-18 with a 4.67 ERA (192 ER/370.0 IP) in 86 minor league appearances, including 74 starts, in five minor league campaigns.
Russell, 23, is batting .241 (77-for-319) with 20 doubles, 10 homers and 36 RBI in 97 games with the Cubs this season.