I don't have a strong opinion on such a matter, I just thought it was interesting. A player can sign his name however he sees fit, from very neat to very messy to very abbreviated. As someone who has long gone by initials instead of a given first name, I'm not one to judge an abbreviated signature.
I just found it interesting, and wonder if it was the result of signing so many autographs that he couldn't bear writing out his last name, or if it just naturally shortened over time and eventually ended up in its current state.
The first time I saw his signature, it was on this TTM autograph I received from him: