The PB's generate function doesn't randomize the voice parameters. It picks A and B sounds from other patches, morphs, copies the morphed sound to A or B then and repeats this process a few times. Sort of picking the DNA of other sounds and mutating that.
The random elements are which presets A and B parts gets picked from, how much it's morphed, how the morph is copied to A or B and how many times this happens.