Rusin, 27, has pitched for Chicago in parts of the last two seasons, and last year posted a 3.93 ERA (29 ER/66.1 IP) with a 2-6 record in 13 starts for the Cubs. He recorded 22.1 consecutive scoreless innings on the road from July 27-September 12 of last season, the longest stretch by a Cubs left-handed rookie pitcher in club history.
Since making his major league debut with the Cubs in 2012, Rusin is 4-9 with a 4.69 ERA (50 ER/96.0 IP) in 20 career starts. He has walked 35 and struck out 57, and allowed 12 home runs.
The lefthander started this season with Iowa and is 0-2 with a 6.52 ERA (7 ER/9.2 IP) in two starts. He allowed just two earned runs in 6.0 innings in his most recent outing, April 8 vs. Nashville.
Originally selected by Chicago in the fourth round of the 2009 draft, Rusin last season was named a Pacific Coast League All-Star and was 8-7 with a complete game shutout and a 3.35 ERA (45 ER/121.0 IP) in 19 games (18 starts) for Iowa. All told, Rusin is 30-30 with a 3.77 ERA (234 ER/558.2 IP) in 107 career minor league games (100 starts).
Schlitter, 28, has no record and a 6.35 ERA (4 ER/5.2 IP) in six relief appearances for the Cubs since he was selected from Iowa, March 30.