Why So Much Just So-So?
There’s an excerpt below the fold.
. . . A few lucky balls get knocked to the right, over and over, and thus end up at the far right; the opposite happens for some balls that end up on the left. But by far the most likely scenario is that the knocks to the left and the right cancel each other out, and the ball ends up in the middle. There are only a few possible paths a ball can take to the extremes, and many, many ways for a ball to end up in the middle.