"Yeah, it was a shock, for sure," Mantiply said.
Mantiply becomes the second reliever the Tigers have added since rosters expanded on Thursday. Detroit designated right-handed reliever Donn Roach for assignment to open a spot on the 40-man roster.
"This was all decided yesterday afternoon," manager Brad Ausmus said. "It was decided before the game started."
The fact that Mantiply made the jump from Double-A makes the move a bit of a surprise. Though the 25-year-old spent most of July at Triple-A Toledo, he gave up four runs on 11 hits over 8 1/3 innings, walking one and striking out seven.