The quality of the applicant is clearly the superior factor. The very top get two. In low unemployment times, if they are not currently working, odds are they are not top talent. In high employment times, if they are active job seekers, the very best have multiple job offers and at least one will be from a top firm. If they are any good, your top people know them.
Top performers are a hard secret to keep.
Professionals you work with have them in their database. They have skills and experiences that are not in your minimum requirements. The best are taken rapidly. Top performers are publicly recognized in their firms. If you survey your hiring managers on their satisfaction with the quality of the applicants they receive, you can get an idea of their assessment of the quality.