Here are a few notes:

Mordecai Sheldrake (1893-1947)
Leonard Warner (1893-?)
William J. MacCarter Jr. (1890-1960), Attorney at Law, University of Penn graduate
Benjamin Logan Edwards (1894-1949)
Robert Kneedler (1892-1985)

They all seemed to live in or around Norwood, PA. Thus the "NW" on the uniform I believe (though there seem to be more letters on the jersey). William MacCarter is your best bet to find solid info, he passed February 8, 1960. In his obituary it indicated he went to Norwood High School, class of 1909. He then attended a Normal school prior to his enrollment at Penn, from where he graduated in 1915. He returned to Norwood in 1916, here's the link to the 1916 Ridley Township City Directory: http://www.ridleytownshiphistory.com...ts/Norwood.pdf All of the players with the exception of Sheldrake & Warner are listed in the directory. Possibly 1916, since 1917 many of these boys may have been drafted.

Hope this helps good luck. Great photo.