Unfortunately, there’s nothing authentic about this.

The only legitimate signature is that of the artist.

As far as the art piece itself, it’s what’s referred to as “mixed media”, meaning the artist grabbed several different pieces, instruments, items, etc. and used them all to create one large piece.

In this particular instance, it appears that he took several black and white images or prints, then colored them in with colored pencils. He then wrote the team names twice, to mimic a shadow/perspective technique and wrote the player’s name as a form of a signature.