Though Rumsfeld's choice of words was poor, I think a lot of people miss the gist of what he's saying. It's not so much that he attacks draftees as having no combat value, but rather that the costs associated with training and maintaining a conscripted army do not add up.
Meaning that you spend the time, effort, money, and resources to train conscripts, and then after their tour is up they're gone. Back to square one with a new set of conscripts. An all-volunteer army doesn't produce this kind of massive turnover and the costs associated with it; there is far less combat experience "brain drain" over time. And if we as a country have the capacity to maintain an all-volunteer army, why unless absolutely necessary would we ever want to institute a draft and all of the costs associated with it?
Here's the quote unceremoniously ripped from Nash's post:
"And what was left was sucked into the intake, trained for a period of months, and then went out, adding no value, no advantage, really, to the United States armed services over any sustained period of time, because the churning that took place, it took enormous amount of effort in terms of training, and then they were gone."
-- Todd/Leviathn