Effective framework for assessing engineering talent / value?

I feel like we're missing a standard structure for assessing the value of engineers. After looking at the engineering ladders / compensation structures for companies like Khan Academy, Rent the Runway, and FogCreek, I arrived at this general assessment structure for engineering talent:

* Technical Expertise (clean and efficient code, language mastery, editor mastery, etc)

* Qualities (leadership ability, communication ability, maturity level, etc)

* Execution (planning ability, ability to get shit done, hitting goals)

* Scope* (area of impact, sub-component, component level, sub-system, system, business unit value)

Some companies also mentioned "experience" and "public artifacts" such as Github projects. However, I left those out because those only serve as signals for the traits we're looking for. When you look at someones experience, you're trying to get a sense of where they're at in terms of things like leadership ability or technical expertise.

Note: I put an asterisk around scope because it's not so much a skill as it is an area of responsibility. Skillfulness in other areas does lead to expansion in the scope of responsibility for an individual within an organization through promotions, but they're still quite distinct from one another since it's not inherently a skill. Nonetheless, it's a key metric because increasing scope does have a significant and direct effect on your value. You can have flying marks in all three areas of technical expertise, qualities, and execution but work on relatively small system compared to other members of the organization with very little business value.

What do you think of this structure? What do you / your company use?