Soto, 29, returns after undergoing a left knee arthroscopy to ease inflammation one month ago today on May 18. He was batting .161 (15-for-93) with three home runs and six RBI in 28 games this season at the time of his injury. Soto yesterday completed a rehab assignment with Triple-A Iowa, batting .188 (3-for-16) with two doubles and one run scored in five games.
Maine, 27, begins his third stint with the Cubs this season, having posted an 0-1 record with a 6.35 ERA (4 ER/5.2 IP) in six relief appearances during his first two big league stops this year. The lefthander has limited major league opponents to a .105 batting average (2-for-19) and struck out 10 in 5.2 innings pitched, an average of 15.9 strikeouts per nine innings pitched. He has seen action with the Cubs during parts of the last three seasons.
With Iowa this season, Maine has gone 3-2 with five saves and a 3.42 ERA (10 ER/26.1 IP) in 22 relief appearances, including a 0.79 ERA (1 ER/11.1 IP) in his last 10 outings starting May 25.
Dempster is 3-3 with a 2.11 ERA (19 ER/81.0 IP) in 12 starts with the Cubs this season. He currently owns a 22.0-scoreless-inning streak.
Castillo is batting .206 (7-for-34) with two doubles, one home run and four RBI in nine games with the Cubs this season. He is hitting .320 (16-for-50) with four doubles, two home runs and eight RBI in 16 contests with Iowa this year.