I love these old pics from the sports equipment companies. I have a new Unitas MacGregor that arrived last week and I'll get that scanned and posted soon.
His sig always looks exactly like this:
And it did even back when Bowman used it on their 1954 Pierce.
The 'cut' sig above is actually from this postcard/photo that I got this summer. The photo was originally taken in 1951. The uniform shows that much. The pic was taken by George Brace who took thousands of photos of major league players for over half a century. The story of his incredible photo inventory and how it was 'stolen' by notorious hobby con artist John Rogers and never legally returned to his estate (his daughter, Mary), is pretty tragic.
The Brace photo is blank-backed other than the name 'Pierce, Walter' in pencil. Walter is Pierce's given name.
At about the same time I found and bought the below postcard of Pierce from his days with the San Francisco Giants: