his learning curve is a little steeper than the others... that doesn't convince me the otb games were fraudulent.
For chess, maybe your rating doesn't mean anything until you've gone through a "verified" bunker-play tournament that operates as a sort of baseline for your ability at all subsequent games until the next one.
For example, if you were watching WCC, one cannot conclude who is better by simply looking at game 9 out of 14. Comebacks happen often.
Even the ELO rating has its drawbacks in determining true strength of the player.
If Magnus plays Hans for 5000 games, sure. Not a chance, at least statistically speaking, in 10 games.
Famously Kramnik, one of the greatest players of all time, blundered mate in one at classical time controls, which is literally a beginner-level mistake.