Once you have a correct set of components, BPM can allow you to recompose them at will into new processes, and SOA can allow you to deploy and execute them on an enterprise (or even inter-enterprise) service bus. But, neither BPM nor SOA can, together or singly, tell you how to define the correct components you'll need at either level, much less how to synch these up. With MDA, we can paint a much clearer and more compelling picture of the BPM-to-SOA approach.