Getty Images says:
Mark Grace #17 of the Chicago Cubs throws the ball to third base during a May, 1990 season game.
Yep, checks out.
It’s clear even from just looking at how Grace is throwing the ball that this isn’t game action. He’s clearly lobbing the ball around the infield as players warm up between innings.
This is confirmed by the view of the auxiliary scoreboard on the facade of the upper deck. It shows the Cubs leading the Dodgers 1-0, heading into the sixth inning.
This game was played Wednesday, May 23, 1990 at Wrigley Field. The weather conditions in the boxscore are noted as “55° F, Wind 7mph in unknown direction, Overcast, No Precipitation,” which pretty much matches what we see in this photo.
Mike Harkey was pitching for the Cubs that afternoon and the Cubs extended their lead to 3-0 entering the eighth. Harkey ran out of gas — in modern baseball, he’d have almost certainly been lifted before that inning, as he had thrown 87 pitches through seven.
But Don Zimmer left him in and he allowed three hits and a run, but got a couple of outs. With two out Zimmer pulled Harkey for Paul Assenmacher, to face the lefthanded-hitting Kal Daniels. Daniels smacked a three-run homer off Assenmacher and the Dodgers went on to win 4-3.
I’m not quite sure how this photo managed to survive all these years; we don’t often see photos of warmups like this, and why it was even taken is lost to the mists of time.