According to eBay's policies on seller standards (http://pages.ebay.com/help/policies/seller-non-performance.html), a seller must maintain less than a 2% negative feedback rate in a specified timeframe (3 calendar months for this seller) to be rated as a "top seller." The minimum standard is 5% negative feedback. Sellers with performance significantly low eBay's minimum standard will have their activities curtailed. While 2,521 negative reviews seems pretty high all on its own, the negative ratings account for roughly 0.73% of their total feedback, so they appear to be well above the minimum.
Wow 283 negatives in a month, but they sell 37,000 in a month. They seem to do a lotta business on EBay and don't care if people don't receive product.