Often the optimal route is to temporarily realign senior staff to effect major change providing the need to backfill with experienced general management skills.
In this case it's important that the interim manager is experienced, can get in-step with the company quickly and can take on all day-to-day activities and decisions immediately.
However where scale, complexity or sensitivity come into play the need for programme management capable of working with a high degree of uncertainty, to create order and clear objectives and to motivate and encourage large cross-functional teams is paramount.
If the need is for a step shift in operational performance it can often be faster and more effective to face-into the problems and take a zero-tolerance approach to the provision of poor service or product.