@zelch The thing is the only way to find a good writer is to find someone who is experienced in your field since they will be writing for your industry on YOUR brand's behalf. Obviously you want the best of the best. I think you are better off doing more of a quality angle versus quantity (sheer volume), cause talking to reporters is something I would reserve for founders or the PR department of my brand versus some intern or low level employee. That is not something I would outsource cause it's so critical to my brand's perspection.
However I imagine it is possible to get a VA to handling the requests and filter them to a more senior person, who writes bullet points of what should be talked about, then gets the VA or someone else who is experienced to write the content and send it off to the reporter.
I found HARO quite useless, especially when most queries require US based writers/businessmen. I do read those queries and respond to them but never had a success so far.
Recently, I got a call from HARO (or the company that bought HARO??) about advertising packages and I politely, yet firmly, refused.
If I was using HARO properly, I would not outsource it. Maybe query filtering, as @CCarter mentioned above ... unless I had internal copywriter or someone who writes exclusively for my company.