McGowan was shut down late in Spring Training because of plantar fasciitis in his right foot. He remained at the club's training facility in Dunedin, Fla., and continues to receive treatment.
"Even though the symptoms are gradually declining it's still there and it's not to the point where we are comfortable putting a ball back in his hand," Blue Jays manager John Farrell said.
McGowan attempted to play catch several days after suffering the foot injury but noticed a change in his arm slot and was immediately shutdown.
Farrell revealed for the first time McGowan also felt some soreness in his shoulder because of the altered angle. That's a major concern for McGowan, who missed more than three years in the big leagues because of multiple shoulder surgeries, but Farrell indicated the discomfort is now gone.
"He felt some soreness in the shoulder as a result of varying the arm slot," Farrell said. "He didn't injure his shoulder but because the symptoms in the heel are still being felt and knowing that he felt that in that game that's why we are being so cautious here."
McGowan was expected to open the season as Toronto's No. 5 starter. The injury caused his timetable to be pushed back to early May and even that now seems optimistic following such a lengthy shutdown.
The native of Savannah, Georgia, will have to build his arm strength back up once deemed fully healthy and likely is looking at a return in mid-to-late May at the very earliest.
"Yeah, I think it has," Farrell said when asked if McGowan's injury has been more of a setback than originally anticipated. "What that means for the date of return is still open ended.
"Every guy is going to recover at their own rate and because of his personal situation his rate of recovery is slower than normal. We have to listen to him and he's going dictate the pace in which we advance things."