The market has changed because there are a lot of imbalances that make expected returns bimodal. For instance, either the euro is going to implode, or it's not. Either there's going to be a recession due to [insert Europe/China/Japan/Middle East] or there's not. So in the short run returns might depend on the perceived likelihood of catastrophe (risk-on/risk-off).

Also, with interest rates low, return expectations might have gotten low enough that the significant vig of Wall Street is a bigger problem for some strategies.