I’ve been working on many projects that are using Scrum.  My background in project management is from PMI and Kanban, especially using the PMBOK. 

Experienced project managers, trained in the formal practice of project management, can be forgiven for feeling that they have entered the Twilight Zone on first encountering Scrum. While Scrum is a “process framework,” optimized for managing software projects, almost nothing about it seems familiar to someone with a PMP certification. And yet, if Scrum is about project management, its concepts should make sense to “classic” project managers.  How can we resolve this paradox?

The apparent discrepancy between Scrum concepts and standard project management concepts is due partly to unfamiliar terminology, and partly to unfamiliar tradeoffs. Let’s look first at the terminology.

The correspondence is straightforward. The burndown chart, for example, is just the graph of remaining planned work versus time, which should trend down to zero on the last day of the Sprint. The Sprint Backlog is the set of requirements (“Stories,” in Scrum) planned for implementation in a Sprint.

Tradeoffs The key to understanding Scrum is to understand what success means for a software project, since the definition of success drives the process.  Project managers are familiar:

"Iron Triangle”: scope, schedule, and cost

For any project, changes to any of these affect the others. For example, if the scope (or effort needed to achieve it) was underestimated, cost and schedule may have to increase to achieve the scope.

The traditional definition of success requires implementing the planned scope, on schedule, and on budget. When this isn’t possible, the next best thing is to trade off, perhaps extending schedule, adding resources (cost), or reducing scope. In most cases, however, achieving the specified scope, or something close to it, is the most significant part of the definition of success for the project.

Software development shops vary.  Not one methodology for project management (PMI, Scrum, Kanban) will fit for all.  You may even find yourself making the most of both – great resource here.

Conclusion
The apparent departure of Scrum projects from standard project-management concepts turns out to be an illusion. In fact, Scrum processes are tightly-choreographed and involve careful planning, as any successful project does. The illusion of otherness arises from the unfamiliar terminology, and an unfamiliar tradeoff of scope versus schedule. In the end, an effective Scrum project is indeed following sound project-management practices.