Al Yellon created Bleed Cubbie Blue and has been its managing editor since 2005. His latest book about the Cubs is "Chicago Cubs Firsts." Find him on Bluesky at @bleedcubbieblue.bsky.social
Getty Images says:
Willie Stargell #8 of the Pittsburgh Pirates bats as catcher Steve Swisher of the Chicago Cubs and umpire Bob Engel look on during a Major League Baseball game at Three Rivers Stadium in 1975 in Pittsburgh, Pennsylvania.
We have almost all the information here, except for the exact date. The year and the three people in the photo are identified.