Buying excellent companies when they are out of favor can be a winning strategy over the long term.The Dow Jones Industrial Average is known for containing 30 industry-leading components from a variety of stock market sectors. But even Dow stocks can endure steep sell-offs.Dow components Salesforce (CRM 1.37%), Chevron (CVX 0.35%), and Home Depot (HD 0.09%) are down between 12% and 24% from their 52-week highs and are all down year-to-date despite gains in the broader indexes like the Dow, S&P 500, and Nasd ...