He wore Blazers in and around late '76. See the photos that accompanied the Dick's Pick release for September of that year for example. But certainly for this era- rare indeed.

That building in the background was painted dark green because it loomed beyond the centerfield fence @ Silver and was thus the backdrop for hitters who played baseball there. If it was a light color for example the white of the pitched baseball would be too difficult for the batters to see. The building is now painted white as baseball isn't played on this site any more; Silver Stadium is gone.