The reason for lower returns recently may be due to the popularization of simple value strategies, but I think it's more because the market is still working off the massive overvaluation of the late 1990s Dot Com boom. (greenbackd.com)
Innumerable studies have shown that simple value strategies outperform the market over time. (charlessizemore.com)
Figure 1.2 below taken from our book shows the cumulative performance of Graham's simple value strategy plotted against the performance of the S&P 500 for the period 1976 to 2011: (greenbackd.com)