Here is a listing from Hunts 2005 for a similar bat.
http://www.huntauctions.com/online/i...um=7&lot_qual=
For a bat or any item that could be c.1911 - 1915, it's not unusual to see a listing describe as 1910. Not too far off, and I have seen far worse. I assume the seller is giving a general/approximate date. Good for you that you are doing your own homework, as all should.
The bat on eBay is a very nice bat.