The comments do raise an interesting question, just how good are the authenticators -- even the honest ones?
Some forgeries are so good, and they are coming so fast and furiously, I don't see how authenticators can possibly stay on top of them all. Some forgeries are so good that -- if viewed by themselves -- it's impossible to tell they are fake. You can only confirm it's a fake when a large number are identified coming from a single source, and they all have the same characteristic. By the time the pattern and the "tell" are identified, there are probably already numerous numbers of these exemplars that have been "authenticated." This further muddies the water because now some people will claim that celebrity signature style "x" must be real because here is an example that PSA (or whomever) authenticated.
As far as Mickey Mantle goes... what value does a forensic examiner really add? If the photo stock and pen type pre-date Mantle's death in 1995, "forensically" the item could be authentic. The same could be said for any modern celebrity.
Certainly authenticators have their value and do perform a valuable service by weeding out a lot of fakes. But don't be fooled into thinking their opinion is anything more than that -- an opinion. And more often than anyone wants to believe, they are wrong.
I recently uncovered a disturbing finding that will have a lot of collectors in denial regarding something they were certain was authentic. I need to get it written up and some pictures posted, but it won't be pretty. Stay tuned...