Most leaders, when challenged to rank order the skill or contribution level of the people in their team, tend to think about aggregate capabilities. “Sue is better than Michael, and Michael is more experienced than Jill.” If you ask them to quantify how much is better, you’ll usually hear “Sue is 10-15% better than Michael. Jill is 10% better than Michael at writing code, but Michael more than makes up for that with his years of experience.”
That’s understandable and useful for aggregate capabilities and potential. Each of us are a gumbo of skills and experiences.
I encourage you to sharpen your thinking about quantifying specific skill areas in your team members, or in candidates for open positions. The distribution of individual skill/experience is likely to follow a power law. The best software developer using .net in agile environments is probably 10x better than the average developer, who is likely to be 10x better than the worst. Not 10% better or worse, but 10X. Often was makes someone 10x better is a prior set of practical experiences. Those same individuals might be flipped order if you’re talking about using python as an individual contributor in a bioinformatics team. Context matters!
100x differences between best and worst are common, and occasionally you will find 10,000x differences. (There are a million software developers who are infinitely better than I at writing .net code!)
Thinking in terms of power laws for specific skills helps you articulate a better rationale for selecting one person over another for an assignment, role, or position.