“Nothing endures but change” is a quote attributed to Heraclitus, a Greek philosopher, who was active around 500 BCE. Change has been a constant in my entire 40-year career, and I have hired and worked with many consulting companies that specialize in strategic change management. The consultants would tell me that change in any company is always difficult to implement, and there are different steps to follow depending on the situation, but in the end effecting change involves one or more of three levers: people, processes, and organization structure. They would go on to say that changes to processes are the hardest to implement because of their interconnected nature and the tendency to incur resistance from staff throughout the company. When planned well, changes to organization structure are easiest to manage because they can be implemented relatively quickly and people tend to adjust to new structure. Changes to people and teams can be challenging and it is best to make those selectively to fit with career interests, retirements, and changes to organization structure.  
When a company is in a crisis, we often read about changes in organization structure, people leaving the company especially at executive levels, and changes in the composition of critical teams within the company.  Changing internal processes, on the other hand, is hardly newsworthy and not the hallmark of someone perceived as a strong executive.  It is no wonder that restructuring is a key feature when new CEOs are appointed and implement a new direction (or old CEOs want to keep their jobs).  Restructuring is a well-travelled transformational model, long advocated by leading strategic consultants.  In fact, the investment community has become accustomed to these types of changes and views them as an indication of an executive in action, taking charge, and leading the company into the future.  
In our book, Applied Leadership Development:  Nine Elements of Leadership Mastery, Leanne Atwater and I challenge the typical consultants’ change model.   We conclude that great leaders consider a fourth lever in a transformation and that is behavior.  Our model includes the following:

People - Changes to people and teams are challenging, and should be done thoughtfully, keeping in the mind the diversity of team composition.  High-performing teams don’t just happen; leaders nurture them into existence and it takes time. 

Process - Changes to processes are difficult to implement effectively, especially if they involve enterprise processes like procurement, logistics, manufacturing, etc.   However, subtle changes to leadership processes like performance management and rewards can have far reaching effects for a company.  For example, changing the standard used to set a performance target can affect what employees observe in the environment and change their focus from incremental, to step change, to breakthrough decisions and actions.  Altering the selection of metrics in a performance management system can transform the identity, purpose, and long-term viability of the organization over time.  Adding a bonus element to a reward system can strengthen the alignment of employee behaviors with the direction and goals of the organization. 

Structure - Organization structure is much more than a formal system of internal tasks and reporting relationships.  As an enabler of change, structure is the hardest change lever to implement successfully because it impacts behaviors, attitudes, relationships, teamwork in the short-term, and ultimately culture in the long-term.  Great leaders use subtle changes in structure to sharpen performance and massive restructurings sparingly when the objective is to alter an organization’s culture.

Behaviors - The criticality of behavior as a causal factor in the success of a person and an organization is compelling.  Great leaders know that their behavior is never neutral—it’s contagious, can ignite passion, evoke trust, and inspire success.  Leaders know that behaviors are not a consequence of what the organization is; it is an input to what it can be.  As a result modeling desired behaviors and nurturing the same in others is a change lever that can be enduring.
We believe that successful change efforts in organizations should focus primarily on leadership processes and behaviors, followed by changes to people and teams.  Massive structure changes should be used when the objective is to change the culture of the organization.