Yes, the longer the game is the closer the average will be to the true average. But given a fixed or bounded game length, you can play enough games to get as much deviation from the average as you want.
Again, the numbers need to be run. There's no way to tell without them, the truth could be either way.
> But given a fixed or bounded game length, you can play enough games to get as much deviation from the average as you want.
If "you" is some abstract entity with infinite time, perhaps. Even if you do ten three-hour runs a day, you can't actually get a very high deviation from average in any given century. Getting a certain deviation requires exponential time in proportion to the number of RNG calls.
You're assuming those are random numbers. As the article says, they are only semi-random (that's one of the big surprises they found).
And you can see from the numbers that it's not just Mitchell's values that deviate from the expected mean, it's the others as well (he's just more extreme), which also shows we can't expect them all to converge to the mean, there's some more complex statistical process going on.
His deviations being more extreme might be explained by him playing more games, or it might be cheating. So far we can't tell.
Again, the numbers need to be run. There's no way to tell without them, the truth could be either way.