I think hiring and setting the appropriate expectations up front and specifically hiring to the desired sales skill set is extremely important.
Many organizations start reps in an inside role with the desire to quickly move them to an external direct sales role. Most people in my experience struggle to execute the multitude of sales skills needed to be successful in either role. Let’s face it; a majority of sales people have no interest in working the phones aggressively let alone daily. So I think you have to tread cautiously on moving someone from inside sales to outside sales unless you measure their goals on the inside role very carefully. If they have always wanted to do direct sales but are willing to put him in some hard hours and months on the inside path to also learn that skill set then I think you can take a chance occasionally. However moving these people to a direct sales role too quickly can also prove a mistake. I would argue that you can become very good at both skill sets, however not everyone can master both of them and ultimately at the end of the day you have to test and evaluate on where they appropriately should fit.