From the leading gain in commodities last month to the bottom performance in REITs, the markets have returned to something approximating normality in terms of return distributions on a monthly basis. Rest assured, the leaders and laggards will evolve, but the odds look higher now for a divergence in returns in any given month.

As a result, the case for owning and managing a multi-asset class portfolio is stronger. Much of what's unfolded over the past year suggests otherwise, of course. The crash of late-2008 slashed prices in most asset classes, which was followed by a sharp rally in the same this year since March. But the high-correlation roller coaster in everything may be over. If so, nuance and subtlety are returning to the business of designing portfolio strategy. That's no surprise given the outlook for the global economy, which reflects a diverging mix of expectations.

The all-or-nothing trade is over. In fact, that constitutes progress. But you'll have to work harder in the months and years ahead to beat the market portfolio. In fact, that's the norm, the last 12 months being the supreme exception of modern times.

The shift back to a standard profile of return, correlation, volatility and other metrics among the major asset classes has only just begun. But this trend has legs and strategic-minded investors should take note.