Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

The Asset Allocation Paradox
I recommend you take a look at this lecture (really, the whole series is enlightening), from Swenson. He identifies 3 sources of returns: diversification, timing and selection. He appears to discard timing and selection as impossible. A student kinda calls him out on this. Diversification reduces risk, not increase returns. It turns out they did time the market, by shorting .com's before the bubble, and real estate just before the downturn. In 1990, Yale started a "Absolute Return" unit and allocated like 15 percent to it, mostly by selling US equities, that specializes in these sorts of hedging moves. As for why you might employ managers for specific areas, consider that the expense ratio Wall Street charges you or me still represent a very nice salary when applied to the billions in Yale's portfolio. So they hire internally to reduce expenses, and I'm sure they're kept busy. They also need people to sell off assets to maintain ratios, and figuring out which ones to sell might take specialized knowledge. Finally, in some areas, you functionally cannot invest without management. For example, Yale has a substantial allocation in private equity, and by definition that doesn't trade on the open market. The other thing you should consider is that for all its diversification, Yale lost 25 percent of their portfolio in 2009. For a technique that's supposed to reduce volatility, they seem to have a large range of returns over the past five years.