Here is a closer look at the decal:
Paul Lukas from UniWatch originally posted this shot of Lou Brock wearing the helmet decal at the 1975 All Star Game
We now have a few more shots of the helmet to add to the collection. Here is another shot of Lou Brock
This newswire photo is dated April 9, 1975, so it appears that the Cardinals introduced the batting helmet decal at the beginning of the season:
This newswire photo is dated April 23, 1975 and gives a better look at the helmet:
This photo of Lou Brock stealing 2nd shows that the logo was worn on both sides of the helmet:
And finally, we can confirm that Lou Brock was not the only Cardinal wearing the decals, as we have pictures of Bake McBride
and Ken Reitz with the decals on their helmets as well:
Its not clear how long the Cardinals used these decals in 1975 as photos from later in the 1975 season do not show the decals. For example, in this photo from August, 1975, Mike Tyson's batting helmet does not have the decals:
The only other place I've seen this logo is as a 1976 Fleer Iron On:
The logo is also shown on the back of the wrapper:
If anyone has seen any other appearances of this logo (perhaps in a Cardinals program or yearbook from 1975 or 1976), I'd be interested in hearing about it, since it appears this logo made just a very brief appearance before the Cardinals decided to retire it.