According to manager Robin Ventura, Leyson Septimo will work as a left-handed specialist and Nate Jones would serve as the team's long man. Santiago, meanwhile, will stretch out at Charlotte and get to start.
Joining the starting rotation is the goal for Santiago.
"Yeah, maybe in the future he could be," said Ventura of Santiago. "Right now, it's better for him to do that when he goes down there, get innings, get stronger, use more pitches.
"You start going through what you need and the stretch run, just a numbers thing. It's unfortunate. He's done well. He ended up being the guy.
"More of it is he'll start games when he's down there instead of relief," Ventura said. "He's been in relief most of the year. You don't know how he'll be used when he comes back but the possibilities open up for him."
The White Sox have four righties and two southpaws in the bullpen, with three rookies and three veterans.