Manager Walt Weiss is hoping the right-handed Oswalt will need just one rehab start before rejoining the Rockies' rotation but called that the "best-case scenario."
Oswalt, who turned 36 Thursday, struggled in four starts with the Rockies, but Weiss still sees potential in the former Astros ace.
"We want to get another look at Roy, see if there's a fit even beyond this year, and if he can perform like we think he can, he's going to be a fit for us," Weiss said. "So it's nice to have that veteran guy around that brings a lot of wisdom, a lot of competitiveness. It would be good to get a look at him here down the stretch."
Oswalt lasted through the sixth inning just once in those four starts and allowed four runs or more in every start except his final one, which lasted just 1 2/3 innings because of his injury. He is 0-4 with a 7.64 ERA, numbers that are slightly worse than those he posted last season with the Rangers.
"There's a lot of things we like about him," Weiss said. "I still think he can perform. I know his numbers aren't what he would want them to be, but I think there's still a lot left."
Ian McCue is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.