The error being avoided
An average month is an average over gate histories, not a month.
The benchmark's unconditional tier distribution blends every gate history the simulated population produced — favourable years spent almost entirely in Growth, punishing ones spent in Buffer and Floor, and everything between. The resulting average describes no individual path's experience. Compare a live month against it and the comparison silently assumes the account's gate history resembled the population average, which it almost never does over a single month. The gap that appears is then attributed to the operator's aggression or timidity, when a substantial part of it is simply which capital states the month contained.
Schematic: the same live month scored two ways. Against the blended average it reads as under-deployment; conditioned on the compressed gate history it actually had, it reads as correct.
