Cubs historical sleuthing: 1970s edition

This photo was sent to me by BCB reader Brian Peterson. Thanks, Brian — and a reminder, if you can find photos you’d like me to sleuth, send ‘em along!

Incidentally, I could have taken this one and made it black-and-white, but this is the way it was sent to me and I rather like the old-fashioned sepia tone.

So what do we know about this photo? The Cubs catcher is wearing No. 9. There’s a Padres runner who was just thrown out at the plate, as shown by the emphatic “out!” call by the plate umpire. A Padres batter wearing No. 21 is clearly the on-deck hitter.

At first, this might seem difficult but in fact, it was pretty easy.

The catcher is Steve Swisher. I recognized him right away. That narrows…