"The artist of this piece is (artist name)". That in itself makes me question the auction.
The artist name thing has me a bit thrown too but I have a few pieces of original art from James Fiorentino that were used to make the Ted Williams tribute cards from Play Ball so it seems plausible that this could be real. I would contact Upper Deck and find out who the artist is and then contact the artist "Gardner" and see what he says. He should know what happened to the original art, if it turns out this is it I would pick it up. It's a really nice and at $500 it's a good deal.
Well now that he added pictures of the COA and is showing the back of the piece I guess there's no doubt this is real.