Hypothetically, if the Jays were to move into a retool, would you still advocate Sanchez to the pen? In a year that probably wouldn't mean much, wouldn't you be interested to see what he can do as a starter?
I agree that as a back end reliever he would be successful. I feel like you're taking this stance though, so that in 3 years if he has failed (as most starters do), you can bring up this thread to say "I told you so". It's really not that bold of a prediction. Guys with plus velocity often don't have a problem finding a job in an MLB pen.
That being said, he has been handled wrong. He should've been left in AAA/AA to work on his secondary offerings. If he makes the rotation out of ST next year, he's likely doomed as a starter, as he'll get shelled because his stuff isn't up to par due to not being given time to develop his secondaries properly. If anything, we should be talking about Sanchez as a September call up next September, and not what his future holds right now.