Manager selection and due diligence is the process of evaluating systematic and quantitative investment managers — including stress-testing their frameworks, interpreting return dispersion, assessing robustness, and distinguishing genuine edge from data-mined backtests.
The institutional response to manager underperformance is to remove the allocation and reallocate to better-performing managers. For systematic strategies, this is backward: a 2-year drawdown in a trend-following strategy that has a 3-year expected drawdown cycle is a buy signal, not a sell signal. The strategy is closest to its expected recovery; recent underperformance has removed the crowded long positions from the strategy; the next period should, in expectation, be better than average. Removing at the bottom locks in the loss AND misses the recovery.
Manager presentations showcase the best-performing parameter set and the most flattering time period. The only way to distinguish genuine edge from backfit is to stress-test the parameters: shift look-back windows ±30%, change rebalancing dates, alter threshold levels. A robust strategy looks similar across this parameter space — a "1940s jeep" that survives all conditions. A backfit strategy produces sharp peaks in parameter space that disappear with small perturbations. Most allocators never run this test; they evaluate on the manager's preferred presentation of data.
A manager who helps clients maintain discipline through a 3-year drawdown generates genuine excess return compared to the mathematically superior manager whose clients exit at the bottom. This "behavioral alpha" is real, measurable, and systematically underpriced in manager evaluation because it doesn't appear in return attribution.