My understanding is that the DoD civilians will serve as advisors in their day job lanes. When I was on the MOD advisory team in Afghanistan, we had an OSD civilian expert who was also an Army reservist. He worked with us as a mobilised 0-6. The rest of the team were primarily contractors. This new program appears to be aimed at filling the gap by providing real DoD employees to overseas missions rather than having to settle for either uniforms or contractors. Alibi -- they could also be used on PRTs in slots requiring their expertise.

Once again, this is just my reading of a bunch of articles out there.