Peavy is out anywhere from four to six weeks with a rib fracture and there is a chance he could be sidelined even longer as he recovers.
Santiago will start for Peavy on Sunday against the Oakland Athletics at U.S. Cellular Field. It will be his sixth start this season.
“I made out the schedule and he's going to be in there for a while,” said pitching coach Don Cooper, who is the acting manager Friday. “And you know, listen, he's done a good job for us. Hey, take these 10 days and pitch twice, go back to the bullpen, stay out there for 10 days, go back out and start. You don't want to do that, but sometimes it's out of necessity.”
In his five starts, Santiago is 1-2 with a 2.96 ERA, averaging just over 5 1/3 innings per outing. In 11 relief appearances, Santiago is 0-2 with a 3.93 ERA. Opponents are hitting .254 against him as a reliever and .216 against him as a starter.
“We're comfortable with him starting, for sure,” Cooper said. “And we'll see how it goes from there, but yeah, he’s penciled in.”