Evolution for rules for evolution vs evoluton for traits
My take is that some of the non-randomness is due to selecting for methods of change itself. So, for instance the ability to make various anatomical structures bigger or smaller was a selection in itself at some point. And the most mutable genes may also be made to be more likely to further mutate, generating a more rapid selection process in one direction. Evolution is like an optimization program (and vice versa in the case of genetic algorithms). But it is an optimization algorithm that is optimizing itself for the best methods of self optimizing.