I was thinking about the Barbell strategy and my portfolio tests and I decided to do some other things. I run a computer simulation for almost every asset mix possible but limiting the computer choices to only 'stock+bills' 'stock+gold' 'stock+bonds' then 'stock+gold+bills(no bonds)' then everything. and told the computer to tell me the best risk adjusted portfolio (looking at the Sortino ratio). The results were
What is interesting is that the computer replicated the barbell strategy (80/70% safe, 20/30% risk) in all portfolios but in one (stock+gold). Stocks had a 4.5% standard deviation (3.51% SD of negative returns only) and gold had a 4.19% SD and 2.43% SD of negative returns. So they are both pretty volatile, which is why the computer didn't find much benefit in barbelling that.
Bonds and bills are far less volatile so the computer quickly found the that it was beneficial to barbell it. This tells me that when mixing assets, it is highly beneficial to think in terms of a 'drawdown' anchor (safe/stable assets) and a 'volatile asset' (usually stocks). That is how one achieves good risk adjusted returns (and a high sortino ratio SHOULD, most of the time, be a good indicator of the best CAGR to max DD portfolio, among other risk adjusted metrics)
I believe that's why the barbell works, it has a very good and stable 'drawdown anchor' (the safe allocation, which is very high at 70-90%) and a small volatile asset allocation. When these two get unbalanced, that's when the drawdowns occur (when stocks do their thing and drop a lot, as they like to do) and risk adjusted returns suffer
This is not to say that bonds are perfect, in fact, I was perhaps too hard on cash in the past, I can see now that the true value of cash lies in being a 'drawdown anchor', limiting total drawdowns. in that respect it can serve a very useful function. Its that smart bond, cash, gold mix that can produce a really powerful drawdown anchor that will be resilient to deflation/inflation/stable periods. with that 'rock' in place, one can then afford to take stock risks (in fact, a lot of stock risk, like EM equities, small cap stocks, levered hedge funds, etc) while still having small drawdowns due the presence of the anchor. i think that's a good way to think about core resilient portfolios