The article "Bad Beta, Good Beta" explains why some stocks perform better than others by breaking down their risk into two types: bad beta and good beta. Bad beta reflects news about the market's future cash flows, while good beta reflects news about the market's discount rates. Value stocks and small stocks have higher cash-flow betas, leading to higher average returns. Growth stocks and large stocks, on the other hand, have predominantly good betas with low risk prices. This helps explain why the traditional model for predicting stock returns has not been as accurate since 1963.