Posted By:
Scott MosleyHi Brian,
I think the picture shows a contingent of Pittsburgh players on the left hand side (including your great grandfather) and then also a group of Philadelphia players on the right.
So, I think your information is correct that he played for Pittsburgh, its just that he ended up in this picture which happens to show players from both of those teams.
The uniforms on the left look correct for 1915-1917 Pirates
http://www.baseballhalloffame.org/exhibits/online_exhibits/dressed_to_the_nines/uniforms.asp?league=NL&city=Pittsburgh&lowYear=1915&highYear=1917&sort=year&increment=9
The biggest evidence, if you look closely, is the mug of Honus Wagner smack dab in the middle of the picture in the back!
Great picture!
Scott