Mark Prior did see Dr. Yocum yesterday, but did not have the MRI until today, reports MLB.com. As a result, results will not be discussed until Saturday. The initial diagnosis, though, is a posterior shoulder strain. Cubs athletic trainer Mark O'Neal's optimism indicates that the tear is partial, as opposed to complete.

Questions: Don't all pitchers have shoulder strains to some extent? And if that's all this is, and given Prior's past history of having MRIs that turn up nothing, how much of Al Yellon's criticism that "Prior sometimes seems like a bit of a baby" is true? I am utterly unqualified to answer these questions.

UPDATE (7:55pm): So much for the MRI results not being available right away. The MRI confirmed the shoulder strain (a moderate one to the subscapularis), reports MLB.com.