A losing month can come from two completely different places, and they look identical on the equity curve

[Shadow Trader]

One is the strategy: the idea stopped working because conditions changed. The other is execution: the idea still works, but entries filled worse than planned, spreads were wider than modeled, or orders were placed late. Both produce red numbers. Only one calls for rewriting the rules.

Things that look the same but are not:

- A drop in win rate caused by signals failing, versus a drop caused by fills landing a pip further from the level on the same signals.
- Smaller average winners because targets are not reached, versus smaller winners because exits were slow.
- Fewer trades because the market gave fewer setups, versus fewer trades because of missed entries.

Separating them means comparing each live trade with an ideal version of itself: the same signal executed at the signal price with the modeled spread. The gap between the ideal curve and the actual one is execution cost. The gap between the ideal curve and zero is strategy quality.

Doing this regularly turns a vague bad feeling into a number that points somewhere specific.

Do you keep a shadow record of ideal fills, and how large is the gap on your account?