This is, obviously, Ryne Sandberg scoring a run against the Cardinals. Getty Images chose to focus on the other player in the photo (typos fixed):
Tony Pena #26 of the St. Louis Cardinals takes the throw as Ryne Sandberg #23 of the Chicago Cubs slides in safe at home during a Major League Baseball game circa 1987 at Wrigley Field in Chicago, Illinois. Pena played for the Cardinals from 1987-89.
That narrows this down, though I would have been able to look up the 1987-89 years for Pena regardless.
Pena played in 26 games at Wrigley Field in the three years he was a Cardinal. That’s a lot of games, but we don’t have to look through all of them. We only have to check the games in which Ryno scored a run, among those 26. There were 11 of them, and we can eliminate one right away (September 25, 1987) because Pena was only a pinch-hitter in that game and did not play the field.
We can also eliminate four other games in which Sandberg scored exactly one run, and it was on a home run. That leaves six games. One more game (April 12, 1989) is crossed off because it was a night game. So we’re down to five games to search. I eliminated one more (September 10, 1989) because Sandberg’s only run that day came as part of a two-run homer by Dwight Smith, no slide needed there.
Now, let’s get down to business, four games remaining to search.
June 6, 1987: Sandberg scored two runs. Both were from scoring position on extra-base hits and those wouldn’t require a slide. So cross this game off the list.
June 12, 1989: Sandberg scored two runs. The first was on a home run, the second from scoring position on a double. This game gets eliminated.
September 8, 1989: Sandberg scored three runs. He homered twice, so it’s not either of those, and then scored from first on a double. That one is possible, but the boxscore says it was cloudy and rainy that day, and it’s clearly a sunny day in the photo.
That leaves only one possibility: Tuesday, April 7, 1987.
Sandberg scored one run, in the first inning. He doubled and advanced to third on an error and scored on a sacrifice fly. There easily could have been an attempted play on him at the plate.
This has to be it; by process of elimination we have eliminated all the other runs Sandberg scored while Pena was playing against the Cubs at Wrigley Field as a Cardinal. April 7, 1987 was Opening Day and it would have, back in the day when not every game was photographed, been logical for that game to be staffed by a photographer. The boxscore doesn’t indicate the weather that day, but the Tribune archive says it was sunny with temps in the mid 60s in mid-afternoon, which matches the photo pretty well.
The Cubs took a 3-0 lead into the third inning, but Rick Sutcliffe had a bout of wildness. He walked seven in fewer than three innings (including five in the third inning alone) and the Cubs lost the game 9-3.
Sutcliffe recovered to have a near-Cy Young season that year. The Cubs, unfortunately, lost 87 games.