[andrepd]

Doesn't than line of thinking mean that anybody can accuse somebody of cheating when they unexpectedly beat them?

[stouset]

No, it means that the reality of catching cheaters in chess is fundamentally heuristic if you don't manage to catch them red-handed.

This accusation hits many of the heuristic high notes.

That doesn't mean he definitively cheated. But to me, with ~15 years of chess under my belt, it does make this accusation credible.

[yesseri]

Niemann have admitted cheating before when playing online, so Carlsen is just not making this up about any random player. There is a history of cheating.

[diehunde]

Also Carlsen didn't accuse other players of cheating the other times he's lost

[lupire]

The sample size for that is absurdly small. (Carlsen only takes single classical losses seriously, since rapid/blitz is too random.)

[ddalex]

There is no smoking gun, but there is a lot of smoke. The ease with which Niemann pulled out of the hand a couple of brilliant moves, without spending too much time thinking about it, on an unusual line, is highly suspicious.