I don't know if this is relative or not but since no one is posting I'll add my two bits , Yours does match others that have been offered for sale even to the color of the ink.
That being said his vintage signatures are very different from those generally accepted as "later in life" signatures. Maybe he signed a stack of 100 index cards one day when he was sitting around. Back in those days the football Hall of Famers were not being deluged with autograph requests so 100 would have went a long way. Or maybe someone else was signing for him all along
It may be relative to an old baseball player (can;t remember his name) but some hobby vets might be able to help here , anyway.... Through the mail requests were answered promptly until someone discovered he HAD BEEN DEAD FOR 10 YEARS , Turns out the wife had been signing for him all along before he died and figured why let something as insignificant as his dying stop her from doing what I guess she must have liked to do.
Not sure if this solves the mystery for you or only makes it more complicated
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