[RUKen]

I have just found a couple of very similar photos in the newspaper archives, with player IDs. The top photo was printed in the Pittsburgh Daily Post on March 9, 1921, and the bottom photos were posted in the Pittsburgh Press on March 13, 1921. I've attached the Bain photo in the middle for comparison. Mangum and Cooper did not join the team until after both of these photos were taken, when the team had moved to Hot Springs.

I keep going in circles with this image. I had believed that the Bain photo was taken in Hot Springs, but I have looked at other photos taken in West Baden (where the Pirates trained in early March 1921) and the background looks like an exact match for the practice field in that location. I had revised my IDs in post #340 substantially when I thought that the image was in Hot Springs. With Cooper in the picture (and I no longer doubt that it is him in the bottom row), then this can't be a 1921 image, because he joined the team after they left West Baden.