Manager John Farrell said the move was made for precautionary reasons and remains optimistic that Alvarez won't have to miss a start.
"We don't anticipate that, but we'll make and take every precautionary measure we can to ensure all of that," Farrell said. "His health is first and foremost in our minds.
"I wouldn't categorize it as an injury right now, even though he left the game with some stiffness," Farrell said. "It's on the inside part of the forearm. I wouldn't say it's over the ligament area, but the MRI will indicate more tomorrow."
http://toronto.bluejays.mlb.com/news/article.jsp?ymd=20120625&content_id=33923180&vkey=news_tor&c_id=tor&tcid=tw_article_33923180
We should know more later today.
if he had soreness of any kind though, he should probably go on the 15 day DL just to be safe(assuming theres no structural damage to his elbow)