Santos, who is on the 60-day disabled list, hasn't pitched since April 20 because of right shoulder inflammation. He recorded two saves this season after saving 30 games last year.
If Santos can take the mound this weekend, manager John Farrell said the right-handed pitcher will be reevaluated to determine the next course of action.
"Any time you take that type of pitcher out of your bullpen, the effects of that are going to be felt," Farrell said. "You've got a guy that's 13 or 14 strikeouts per nine inning rate that is removed that had a solid year closing out games last year. We went through some unsettled portion of time where we had to readjust some roles."
Casey Janssen has filled in admirably for Santos, saving 11 straight games entering Friday since becoming the Blue Jays' closer. Farrell said Janssen's taken advantage of hitters' aggressiveness in the ninth inning, when their sense of urgency is heightened.
"We knew he was going to throw strikes, control the running game, and had the ability to get both left-handers and right-handers out," Farrell said. "He has flourished as our closer. I hate to think where we'd be if he hadn't assumed the role."