A client of mine with an open sales position, recently interviewed a rep with 20 years of sales experience. The only reason for the rep's job search was that their former employer had gone out of business. Given their experience and tenure, my client wondered if it was it necessary to administer a pre-employment sales assessment before offering them a position? I told them I thought it was very important -- not so much to figure out whether or not they could sell - but to learn about their strengths and weaknesses. No sales rep is perfect -- even 20 years in. They may struggle with elements of the sales cycle that no one has ever discussed or addressed with them.
Let's say this particular rep has an outgoing personality, making prospecting relatively easy for them. Closing a sale doesn't present a big hurdle. However, they struggle when dealing with really forceful objections from a prospect. Over the years they've lost more than one sale because of their inability to address and move on from a tough objection.
Know this before you make the candidate an offer. Instead of being surprised when they can't seem to make headway with a particular prospect, have an idea of what the potential problem might be. Offer help or coaching.
Getting all the information possible about a candidate before making an offer, increases the chances of a successful hire.