I see by your question that you're a recruiter for your organization. So, I'm assuming that your job is to recruit for your managers in the field and help them in the selection process for their respective areas of responsibility. So the key ingredient here is in the selective selection criteria. What is the criteria that you're looking for as a top performer in your particular company's sales culture?
As the recruiter, you need to determine what your manager in the field sees as the qualities for a top performer. What skills are required, what experience, what personal skills, what behaviors? Then you, as a resource, also need to contribute to that manager what your perception is, and you must agree together on what that criteria is to be because your job as a recruiter is to be an asset and a resource to your managers. Your client is actually the manager, so you have to make them happy. Once you and your manager agree, then you move forward to find the people that they want.
The second part of your question was how you can leave a positive impact on those who are not hired. The simple answer is to be upfront with each candidate early in the hiring process. For example, step 1 will be the telephone interview; step 2 will be a face-to-face with the recruiting manager; then if that is successful they would take a profile and then the next step after that would be an interview face-to-face with the manager in the field or whatever that process is. And as soon as the candidate is determined not to be a fit, then a personal phone call to them is made informing them of the decision. Not just an email or a letter, but I would follow-up the phone call then with a letter to leave a good impression that you were prompt and up front with them.