Like an athlete going through a slump, Nike (NKE -1.11%) finds itself at a critical juncture. The sportswear giant's shares have tumbled nearly 30% over the prior 12 months, while the S&P 500 (^GSPC 0.16%) has delivered total returns of 27.5%, including dividends.Despite the sharp decline, Nike's stock still commands a premium valuation at 30.8 times forward earnings. Let's break down the athletic apparel giant's fundamentals to determine if this contrarian setup presents a buying opportunity at the onset o ...