Those players would be initially quarantined either way and a sliding experience window would put a limit on what is plausible. Same goes for transferrable skills.
Experienced players who cheat will still be subject to plausibility. Say there is a normal amount of variance in humans but suddenly some player no longer has variance in their action. That's not plausible at all. Or a player looking at things they cannot see, that might sometimes be a coincidence, but that level of coincidence is not plausible to suddenly change a drastic amount.
Again, this sort of thing doesn't catch all subtle cheaters, but those are also not the biggest issue. It's the generic "runs into a room, beats everyone within 10ms", and "cannot see, but hits anyway all the time" type of cheat you'd want to capture automatically.
A what-if in a tournament or the top 1% of players is such a small set of players, you'd be able to do human observation. Even then someone could cheat, but you're so far outside of the realm of general cheating, I wonder if that's worth including in a system that's mostly beneficial inside the mass market gaming players.
Either way, this sort of detection is usually done in the financial and retail world, and results in highly acceptable rates and results. It's not perfect with a 100% success rate or something like that, but it's pretty successful. Just not something studios or publishers seem to want to invest in. It's much simpler to just buy or licence something (like Easy Anti-Cheat). Broad internal expertise isn't something the markets are rewarding at this point.
