I promoted the managers because they were great workers. Can they be good managers?

Maybe. Management ability isn’t innate; it’s learned, like any other behavioral skill. Yet, 50% of new managers report that they received no training before assuming the role. We don’t allow a new employee to run a machine or to enter data without training; should employees who are new to management be treated any differently? The Manager, or immediate supervisor, is the single biggest factor in employees’ engagement and retention. Also, a management development program tells employees that they are valued, and worthy of investment.