After looking at a number of knobs, his hand writing varies. I found a few examples on the web that I believe are consistent with this one. See the "7" in the Mears link. Obviously, my opinion is not objective, but I'm not offering the bat for sale. I would think a collector would have written "19" on the bat. It does have pine-tar as noted by Lelands.
www.mearsonlineauctions.com/lot-84717.aspx