Its probably the avg put into the formula for the wheels 'randomness'.

It in, in fact, not random. Nothing with computers is random. The wheel knows what it is giving you before the whole spin fiasco, so the other pictures are are just for show, they don't matter. It will give you a 'random' item based on a neutral formula, probably used for the whole server that has an average of 24.

Some high...some low.