Pitchers with "good" mechanics get hurt all the time. Danks was not an injury risk and then his shoulder went out last year. It's really just a crapshoot with pitchers.
Back to the actual topic, I am also on the side of only trade Sale for the right deal, don't be too stubborn one way or the other. Sometimes it's better to trade a $100 bill for a $50, two $20's and a $10.