Amazon must know the competitive landscape in retail is significantly different from mail order. Best Buy's ( BBY ) primary business model is retail, and we can see how that has worked against lower-cost online competitors Amazon and eBay ( EBAY ). But is it only "showrooming" from Amazon's customers inside Best Buy that resulted in lower revenue and earnings for Best Buy? I believe Best Buy's greatest competitive environment is from other retailers, not Amazon. Other stores appear to sell the same or similar products. Target ( TGT ), Sears ( SHLD ) and the retail elephant Walmart ( WMT ) offer the lion's share of products available in Best Buy. Instead of focusing on cost control, improving margins and remaining competitive on price, Amazon is counting on greater sales (and maybe earnings) from falling delivery times. Amazon is losing its greatest competitive advantage.