I think you guys just might not be used to in person signatures. I was at spring training this year and got this Koufax ball signed in person. When I posted it fellow members said they would have thought it wasn't authentic if I didn't say I got it signed myself.
He was surrounded by a mob. It's hard to take your time in that kind of environment. But it the most authentic Koufax signature I can attest to, having seen it signed before my eyes:
