Each weekday, TheStreet.com Ratings updates its ratings on the stocks it covers. The proprietary ratings model projects a stock's total return potential over a 12-month period, including both price appreciation and dividends. Buy, hold or sell ratings designate how the Ratings group expects these stocks to perform against a general benchmark of the equities market and interest rates.While the ratings model is quantitative, it uses both subjective and objective elements. For instance, subjective elements include expected equities market returns, future interest rates, implied industry outlook and company earnings forecasts. Objective elements include volatility of past operating revenue, financial strength and company cash flows. Warehouse club operator BJ's Wholesale Club ( BJ) has been upgraded to buy. The company has enjoyed revenue growth, solid stock price performance, reasonable valuation levels, good cash flow from operations and an increase in net income. These strengths should outweigh its somewhat disappointing return on equity. BJ's reported second-quarter earnings of $36.3 million, or 55 cents a share, up from $26.4 million, or 39 cents a share, a year earlier. Powered by strong earnings growth of 30% and other factors, the stock has surged 26.3% over the past year. Revenue increased to $2.29 billion from $2.12 billion a year ago. BJ's should continue to move higher even though it has already seen a nice gain in the past year. The company had been rated hold since August.