McGowan hasn't pitched in the Major Leagues since 2008, when he was forced to undergo surgery to repair a torn labrum.
The 29-year-old was expected to return as a reliever, but his recent success has caused the Blue Jays to re-evaluate that decision.
"I didn't expect to ever even see him being considered a starter again, but he has made such progress," Blue Jays general manager Alex Anthopoulos said. "It's exciting. We're learning as we go through this, as well.
"Your No. 1 goal is to keep a player as healthy as you can, and initially he had so many setbacks, the thought was, look maybe we just need to try to minimize everything and keep him as a reliever."
The Blue Jays have since consulted with their team doctors and renowned surgeon Dr. James Andrews about what the next phase of McGowan's recovery should be. The general consensus appears to be that a set pitching schedule would be beneficial for McGowan's overall health.
A move to the starting rotation would allow McGowan to avoid pitching on back-to-back days, as well as having to continuously be ready out of the club's bullpen.
"A starter's role can be regulated a whole lot more," Blue Jays manager John Farrell said. "In this case, provided he is able to build on those innings incrementally through the rehab part, it might lend us to take that route more in earnest."
McGowan still faces a long road back to the Major Leagues. He currently has only thrown in extended spring training this year, and has not gone multiple innings.
The next step of his rehab will be pitching two innings once every four days. Extended spring training ends June 8, so he likely will then go on a rehab assignment that cannot last more then 30 days.
When that time frame expires, the club must either place McGowan on the 25-man roster or risk losing him to waivers, because he is out of options on his $450,000 contract.
McGowan also can have the 30-day window put on hold or restarted at any time if he is not deemed healthy enough to return.
The biggest positive of McGowan's progression in recent weeks has been his ability to pitch without limitations. The native of Georgia's velocity has climbed all the way back to 95 mph, while his secondary pitches also reportedly have new life.
"When he was coming back before he was like 88, 87, in Spring Training it wasn't close to what it is now," Anthopoulos said. "Stuff wasn't where it was today, now he has bounced back and he hasn't done it just once now, he has done it multiple times. Again, we're going to be as conservative as we can be, we're going to take our time."
McGowan is a combined 20-22 with a 4.71 ERA in four seasons during his Major League career. His best season came in 2007, when he went 12-10 with a 4.08 ERA.