Check out the CRB index. It had a STRONG upside bias 2001-2008. Easy to conclude that successful CTAs also had a long bias... which was correct for the time. Since 2008 peak, commodities have had a strong down bias. If CTAs were prone to still having a long bias (not because they couldn't read a chart but because it's "part of their DNA" as it is for most market players), they would struggle. IOW... the markets' long-side bias hit the CTAs' long side-bias... and VIOLA! Success. But when the market's bias shifted to negative, the CTAs were still trying to BTFD and always give the benefit of the doubt to the long side..