There really is only one person who can authenticate and verify this ball and that would be Derek Jeter. It would be really cool if they got Jeter to examine the ball and confirm it (or not).
UPDATE: I just saw this article:
http://www.nydailynews.com/sports/ba...icle-1.1951962
I guess they did ask him but he doesn't remember signing the ball because it was too long ago.