The extent and location (arm or elbow) of the injury is unknown. Obviously, this is awful news, and I'm certain some will take the opportunity to further criticize the logic behind granting him a long-term contract. Let's hope it's not serious and that he'll return shortly, because a lengthy stint on the DL would be extremely detrimental to the Jays' chances of success.
Update: According to the Toronto Star, the injury isn't serious. Apparently, his discomfort was caused by complications resulting from scar tissue breaking up. Now let's all breathe a collective sigh of relief.