You may be surprised to hear this coming from me, but you might just consider giving the guy a chance.
My current sup was also a "one peak wonder" before being assigned to my center. Its been a little over a year now andn he is actually turning out to be a pretty good one. His lack of driving experience is offset by the fact that he is very tech savvy and has a good eye for detail, which is a lot more important in todays UPS than how many years he spent in the driver seat. He has turned into a pretty good problem solver. To his credit, he was honest and upfront about his lack of experience and has been willing to listen to and learn from his subordinates. If your sup is also willing to display the requisite degree of humility, he could turn out to be OK. Remember this....as the proud owner of a new rookie supervisor, you have both an opportunity and a responsibility to train that supervisor and mold him into the manager that he will someday become. Future generations of drivers will benefit from how you break this man in, and you have an obligation to them to break him in correctly.