You have to realise that the person who is using eBay is not necessarily the same person who owns the card.

eg A person uses their own eBay account, the go to pay, putting their address in the checkout, which is where the PayPal address comes from, so the PayPal and eBay addresses will match, but when they go to pay they use a stolen credit card, or "borrow" a relative's without telling them.

The dispute is not a PayPal dispute, it is initiated with the card provider and the card provider is the one that makes the decision over who 'wins'.

If you have proof of shipping, you should qualify for seller protection and if you do get seller protection it doesn't matter what the bank decides, as you won't lose the funds.

If you don't have proof of shipping you have a much harder task at hand if you try to fight the chargeback - you will need to convince the bank (not PayPal) that the person who purchased your item was authorised to use the card. That will be easier if the cardholder and buyer are actually the same person, but quite difficult if they aren't.