My dad was a Leatherhead...truly. Here he is, sans helmet, circa late 20s
He spent his college ball days as a fullback for Cornell. Then he went into the leagues, which were just starting then, and played for the Long Island Bulldogs. I don't know all that much because my dad was a modest man, and this all had to be pried from him.
It was a really rough game in those days. His fourth finger on one hand only had one joint because the finger was broken in a game and never fixed. He had a red star scar in the corner of his eyelid from someone stepping on his face with their cleats. And he played one entire half unconscious. He was knocked out somewhere at the beginning of the half but never fell down. He didn't come to until the half was over, and in the telling of it, that seemed no big deal to him.
I can't remember why my dad didn't continue playing pro ball, but I can tell you he had little interest in the modern game. "Sissies," he would say, looking at all the padding and high tech helmets they wear today. Padding in his day was Kotex and the helmets, yep, just leather.