Getty Images says:
Wrigley Field circa 1990 during batting practice, in Chicago, Illinois.
Not much of a clue. One thing we do know for sure is that this is BP before a night game — the clock reads 4:40. There aren’t any fans in the ballpark, then as now, gates opened two hours before night games.
It’s tough to read some of the matchups, but the most important clue is the message board beneath the scoreboard, which reads:
MOUNTAIN DEW PICNIC BAG NIGHT
The Cubs’ 1989 media guide lists this promotion as happening Wednesday, May 10, 1989.