“I think the real issue is that many companies don’t realize that, more times than not, they are not going to be able to replace someone who left with a person who has an identical skill set,” says Trevor Simm, President of staffing firm OpalStaff in Millersville, Md. “Many companies lose sight of the fact that their employees, especially those with tenure, have evolved a great deal since their hire date, and have gained knowledge of technologies that are specific to that employer and their environment.”
Trevor Simm is quoted several times throughout this Dice.com article – “How to Approach Impossible Job Postings.”