The test revealed a tear, and as a result Morrow has been placed on the 60-day disabled list. The hope is that Morrow will be able to avoid surgery and return in July, but there is also a chance he will not pitch again this season. The Blue Jays recalled right-hander Chad Jenkins to take Morrow's spot on the 25-man roster.
"If he heals up, he should be back in July; if it's not healing up, then they'll have to do surgery and he'll be done for the year probably," Blue Jays manager John Gibbons said. "They're going to wait to see [about] rehab, see if it heals on its own. But if it looks like it's not going to [heal], they have the option to have surgery."
The injury is yet another setback for Morrow, who has been plagued with a wide variety of ailments throughout his career. In 2012, a strained oblique muscle cost him more than two months, and last year a strained right forearm limited him to just 10 starts.
The hope was that this would finally be the year that Morrow broke through and became a bonafide frontline starting pitcher. The Blue Jays frequently praised his upside during the offseason and early in Spring Training, but when the regular season began he struggled to find any type of groove.
Morrow had a 5.93 ERA in six starts this season, with only one outing lasting as many as six innings. He set a career high with eight walks during a start against the Red Sox on April 26, and though those command issues were solved on Friday night, he still surrendered 11 hits.
Gibbons said Morrow had felt a pop near the base of the finger toward the end of his last inning Friday.
With Morrow on the DL, the Blue Jays decided to nix the idea of going with a six-man rotation. Left-hander J.A. Happ was scheduled to make a spot start on Monday in Philadelphia to give the other starters an additional day of rest. Instead of being afforded that luxury, Toronto has decided to make Happ a member of the current starting five.
It remains to be seen how long the Blue Jays will wait before making additional changes. Marcus Stroman, rated the club's No. 2 prospect by MLB.com, will be called up from Triple-A Buffalo prior to Sunday afternoon's game against the Pirates, but he will be coming out of the bullpen, at least temporarily. A corresponding roster move for Stroman's promotion will not be announced until Sunday morning.
Gregor Chisholm is a reporter for MLB.com. Read his blog, North of the Border, and follow him on Twitter @gregorMLB. This story was not subject to the approval of Major League Baseball or its clubs.