Bluejays.com reported today that Dustin McGowan will have season-ending surgery on his pitching shoulder. That's the bad news.
The worse news is that rather than going under the knife to repair his rotator cuff, which was the injury to which his current DL stint was originally attributed, the operation will focus on fixing "fraying" of his labrum.
Many, including Will Carroll of BP, have written that the track record of pitchers who are able to come back from labrum tears is quite bad. This does not mean that they never make it through rehab or that they never throw another pitch in the bigs, but that they never get back to their previous skill level. If this is the case with Dustin, that is a major setback for any short- and medium-term plans the Jays have to contend (assuming they actually have such a plan, which is no given).
According to Torgen in the last game thread (5 game winning streak, woo!), the location of the tear is important for prognosis (rear tears being worse than front, meaning Casey Janssen's tear might not be terrible). The report said nothing of the location of the tear, so let's hope that DMC is able to come back. I've not heard this before, but I'm certainly no expert on the subject. Information on the topic is welcome.
The surgery will also explore the rotator cuff to see if it needs repair. Seems to me that the best case scenario is that he's back for next spring training nearly as good as new. Worst case, he needs cuff and labrum repair, is out longer term and never makes it back to his current form or reaches his future promise.