"We'll see where it goes from there," Renteria said.
Wada has come a long way since Spring Training, when the lefty posted an 8.38 ERA in four games, giving up nine runs over 9 2/3 innings. On Friday, Wada, 33, struck out 10 for the third time this season at Triple-A Iowa, and leads the Pacific Coast League with 120 strikeouts. He is fourth in ERA (2.77) and fifth with a 1.16 WHIP.
The left-hander picked up his 10th win Friday and joined Hendricks with double-digit wins this year.
In his Major League debut at Great American Ball Park, Wada gave up one unearned run on five hits over five innings.
"The reports and how he's been pitching, he's been working more down in the zone and more efficient with his pitches," Renteria said of Wada, adding that he has been able to "elevate when he needs to as opposed to elevating in a non-elevating situation."
The Cubs signed Wada as a free agent in January, but he didn't impress this spring.
"It was a struggle," Renteria said of the lefty's Cactus League games. "A lot of his pitches were elevated, his command was off. He'd get into trouble and had trouble getting out of it. It was good in the fifth inning of that one game in Cincinnati when he got into a jam and ended up getting out of it."
The Cubs acquired right-hander Dan Straily, who owned a 4.93 ERA in the Majors this year, from the Athletics in the July 4 deal, but he is not ready to join the big league team, Renteria said.
"Right now, the plan is to get Straily back on track," Renteria said. "I can't tell you how soon or how far down the road. We're just trying to get him back on track."
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.