Best to try and resolve issue before asking eBay to step in, depending on the case. If it is for an item not received, and seller has tracking number/delivery confirmation then would be worth it having eBay step in, if looks likely case will be solved in sellers favour.  

Cases closed without seller resolution

A case closed without seller resolution means the buyer reported they didn't receive an item, asked to return an item, or opened a PayPal Buyer Protection case, you weren't able to resolve it, the buyer asked us to step in and help (or escalated the case to PayPal for review), and eBay or PayPal found you responsible.

To meet our minimum standards, you can only have 2 transactions (or 0.3% of transactions) resulting in cases closed without seller resolution over the most recent evaluation period. The percentage requirement applies after the account has exceeded the maximum number of occurrences.