"This free lunch proves that the market is far from perfectly “efficient.” Haugen himself argues it drives “a stake through the heart of the efficient market hypothesis.”
Even members of the efficient market cult have been forced to concede some of these points. For decades they maintained that to earn higher returns, you needed to take on more volatility, or “risk.” Then they looked again at the data and realized it wasn’t quite true. They admitted, instead, that small companies had done better than large companies. And value stocks had done better than growth stocks – even though they entailed less risk."