this is a forgery, in my opinion, and not a very good one. I have never seen Yaz write his first name like this, and connect it to the Y, which is also way off.  the last few letters in his last name are also shaky and not consistent.

http://www.ebay.com/itm/CARL-YASTRZEMSKI-SIGNED-JSA-CERTED-MAJOR-LE...