[Jataman606]

> That would clearly work for someone who is cheating by letting an engine do all the work, but how about someone who mostly plays the game themselves just using the engine rarely?

Thats exactly what those engines try to detect. If you are average player, but every time you start loosing you get significantly better, then there is great possibility that you are cheating. Thats whats looking through history gives you. It's about actually finding deviations from your usual behaviour.