Beginning in March 2008, performance evaluation will be based on a 30-day period. It will also include Item "Significantly Not As Described" (SNAD), and Detailed Seller Ratings (DSRs) of 1 or 2. eBay added these factors because buyers leave 1 or 2 DSR ratings nine times more often than negative feedback, which suggests feedback and INRs alone did not reflect customer dissatisfaction.
Fees 2008 Rewards FAQ (Feb 2008)
eBay requires sellers to maintain minimum standards in buyer satisfaction. Our goal is to ensure that the marketplace is a safe and reputable place for the community to buy and sell. We have found that 1% of eBay sellers are responsible for 35% of bad buyer experiences on eBay. This not only impacts buyers, but is harmful to other sellers and the eBay marketplace as a whole.
Sellers receiving this notification have been identified as part of this bottom 1% of sellers as measured by Feedback and Item Not Received complaints over the past 90 days. If more than 5% of a seller/s buyers are dissatisfied, as measured by negative and neutral Feedback left or Item Not Received complaints during a 90 day period, the seller is in violation of the Seller Non-Performance policy.
You might also want to read eBay's Official Announcement (made about two and a half months after they started suspending sellers).
whb@toolhaus.org