not billy williams?
 

This Sports Illustrated poster, circa '68, was issued as Ernie Banks, but in the guides listed as an "error" picturing Billy Williams instead. I don't think it's either. It doesn't look like Williams. It actually looks more like a guy named Jimmy McMath, who was with the Cubs in 1968. Does anyone know the background on this?

I agree. I think you might be correct, FWIW.

it could also be clarence jones, another leftie with similar facial features ...

I usually avoid modern stuff, and I would like to see a better scan of the SI cover. As best as I can tell the ear is very different from that of Banks, Williams, Jones, and McMath (for McMath I can only compare opposite ears). Of course, he is hitting from the wrong side for Banks.

I'll chime in and add that I don't think it's Williams either. Williams has the largest arms from his elbows to his wrists that I've ever seen and that photo doesn't look even close.

I just now stumbled across this 8+ year old thread. The mentioned possible players are before my time, Jimmy McMath and Clarence Jones, but I'm thinking that it's maybe George Altman?

You could well be correct.... those ears are a great match!

I would bet it is indeed the lefty, Altman. Nice job potentially solving a long-running mystery!

BTW, that particular SI Poster was always my favorite as a kid, and the Sears we shopped at was always out of stock on that one! I remember having Pete Rose, Bob Gibson, Hank Aaron, Don Drysdale, Carl Yaz and Lou Brock from that 1968 group. Great stuff!