Donald Sull recently discussed three styles of management, with management by commitments as the winner, and management by process the runner up. I agree: these are key aspects of Scrum, and two of the reasons Scrum works.Sull's first style management is managing by power hierarchy. This is the old command-and-control style of management. This style just doesn't work in innovation industries. When you are building something new and complex, you don't know exactly what you are building early enough to know what to command and how to control it. You can't know everything to do ahead of time, and you can't control every behavior and task outcome. You delude yourself by inventing fictional project plans, full of deceptively credible looking work breakdowns, effort estimates, and Gantt charts. You get upset when your team veers from your prescribed work sequence, and your team is frustrated that it can't do things "the right way." You all lie to each other and your upper management team that the project is making adequate progress, and then it all hits the fan near your delivery deadline.
The second management style Sull discusses is management by process. Sull criticizes Six Sigman, TQM, and other overly rigid processes as innovation blockers. Scrum responds to this by being light weight. If the Scrum team identifies a practice that impedes its progress and acceleration, then the team addresses at the daily scrum, the sprint retrospective, or just by working closely together and communicating frequently. Scrum's lightweight framework stays out of the way at the right times, and encourages practical improvements as needed.
Sull's third style is management by commitment. He identifies five characteristics of good commitments: public, active, voluntary, explicit, and motivating. Good commitments are made and tracked publicly. The person making the commitment takes an active role in making sure he understands what to do. People make commitments voluntarily, with the ability to say no. The commitment has explicit actors--a person fulfilling the commitment, and person benefiting from the commitment. Finally, every commitment has a motivating rationale.
Sull doesn't say it, but the combination of managing by process and by commitment is Scrum. Scrum is a lightweight process framework, providing enough process to be effective without being stifling. A Scrum team makes its commitments publicly and publishes them on the project task board (see http://www.mountaingoatsoftware.com/task-boards and http://www.scrumalliance.org/articles/39-glossary-of-scrum-terms). Every task that is committed trumps any task that the team hasn't committed to. Team members face each other at least once a day at the daily scrum, where they report their progress against their commitments. The team as a whole tracks its progress against its commitments daily and at sprint boundaries. The team voluntarily makes its sprint commitments as it selects items from backlog for the current sprint. The actors are explicitly identified: members of the team do the work for the product owner. The rationale for doing each task is clear, expressed by the user stories and by the business value and prioritization associated with each story, and further explained and amplified by the product owner as needed.
Scrum teams are successful for the same reasons teams that use process and commitment are successful. Scrum succeeds by trusting people to make and meet commitments in a can-do atmosphere.