How can they really tell an authentic signature?

lightningboy

I asked this on the wrong forum probably so I thought Id pose it here.

I've spent some time looking closely at many JSA or PSA graded authenticated baseballs on Ebay. And although the signatures from any given player appear very similar at first, very subtle differences can be detected from one authenticated sign. to another. This makes perfect sense to me as I know for a fact if I signed my name 10 times in a row, not all signatures will be identical to a tee. Is it truly just an educated guessing game? Any insight or experiences are most welcomed.

timb69

I spoke to a JSA rep about 2 years ago at a friend of mines signing event. They have a database of autographs from all the players, that span across their career showing changes in how they signed. Not to mention all the tell-tale signs of how someone signs, their writing, loops, swoops, etc.