Santos, 0-2 with a 7.78 ERA and five saves, was designated for assignment and placed on waivers. Unless he's claimed by another team, the Blue Jays are responsible for $1,290,984 still owed to Santos this season and a $750,000 option buyout for 2015.
"It's his command, and once he can get ahead in the count he's going to be back to being the guy he was," general manager Alex Anthopoulos said. "We hope this is a quick move, get some innings, get hot and come back because we certainly could use the help."
Anthopoulos said if Santos is not claimed, the team would like him to report to Triple-A Buffalo with the hope he could regain his form. Anthopoulos said the 31-year-old did not ask for a trade and the Blue Jays did not try to deal him.
"He's a very accountable guy. He knows he hasn't pitched to his ability," Anthopoulos said. "He knows he can be a dominant closer, setup guy, whatever is needed."
Toronto filled Santos' roster spot by recalling left-hander Rob Rasmussen from Buffalo.
A converted infielder who once played shortstop in Toronto's minor league system, Santos reached the majors as a right-hander pitcher with the Chicago White Sox in 2010 and was traded to the Blue Jays after the 2011 season, when he saved 30 games. He had season-ending shoulder surgery in 2012, then missed most of 2013 after elbow surgery. Santos was also out for a month earlier this season with a strained forearm.
"It's been a tough year for him," Blue Jays manager John Gibbons said. "He started out good. He's a little out of whack right now. It's tough to find him work."
Anthopoulos said the struggling pitcher would be considered a "priority guy" out of the bullpen for the Bisons.
"We're not in the position to try to work through things up here," Anthopoulos said. "If Sergio goes down there and is pouring in strikes and putting up great stats and great performances, he'll be back very fast."
Rasmussen has no record and a 6.00 ERA in seven appearances with Toronto this season.