Turner was 4-7 with a 5.97 ERA in 20 games (12 starts) with Miami. He was in the Marlins' rotation from the start of the season until June 11, then made eight relief appearances. In his last three outings, all starts, he gave up eight earned runs on 19 hits and six walks over 14 2/3 innings.
Renteria couldn't project what Turner, 23, will do, although he most likely will be used out of the bullpen. The pitcher is out of options, and the Cubs will have to make a roster move when Turner arrives.
"Maybe a change of scenery can help," Renteria said. "We know [Turner] was a highly touted prospect, we know that he has a good arm. Getting him here and putting our eyes on him in real terms and allowing the staff to work with him and see how things develop is something we're looking forward to doing."
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.