In your post above you have 2012 whereas the card from ebay is 2010 so what you most likely have is a buy back autograph card, its just a hard signature on the card instead of the signature on the sticker
This is an example of another sharapova buy back card of a different card
Maria Sharapova 2011 Ace Match Point 2 Authentic Buyback Auto | eBay
Very similar to yours above with the same pen colour.
Hope this helps