On reading the blog below written by Tom Sorensen I can completely understand his pain and frustrations. 

To be fair, this is something if you are hiring directly from the market can happen and is notoriously hard to manage. 

If however you have been using a third party to assist with your talent acquisition demand, then you should have never been put in this position in the first place.

As a recruiter or talent acquisition professional, it is one of your key responsibilities to manage candidates throughout the recruitment cycle. Discussions about counter offers and specific reasons for wanting to explore new opportunities should have been addressed with individuals prior to any introduction to potential future employers. 

If there were any realistic concerns about counter offers from a candidates current employer.  This should have been addressed with the interviewer prior to any initial meeting and a plan of action to manage the process could have been formulated. 

Obviously there is an additional cost of having a third party involved in the recruitment process. However I would argue, that the cost of not having assistance outweighs the initial outlay. Try not to think solely about financial outlay, but the extra physical commitment from your side. The man hours you spend interviewing candidates which could have already been pre-screened and ruled out, the time spent creating role documentation and marketing material which could be been created and managed externally.  

Most importantly however is the benefit of having an ally working in your best interests in mind throughout the sourcing process, representing your employer brand to the best of its ability and finding the candidates with the best technical and cultural fit to your organisation. 

When you think about it, you should never have to feel the pain of an unexpected counter offer again!