There is a photo of the 1882 St. Louis University baseball team on their digital archives, which includes a very young Joe Murphy. I'm posting a link below, because I'm not sure that I can post the image itself due to copyright questions.
http://digitalcollections.slu.edu/di.../id/1496/rec/1
Murphy is in the front row, second from the left, with a smug look on his face (as opposed to Father Joseph Murphy, standing behind him).
Correction: That should be second from the right, not second from the left.