The best leaders on your team may be ignoring your KPIs
When you’re evaluating leadership potential in your team, remember that all the metrics you have are proxy metrics. You can’t easily evaluate such a complex concept as leadership.
If you’ve assigned them metrics, or SMART (spare me) objectives, again you’re measuring proxy. The best leaders go beyond them and do the bigger right thing.
You can measure the quality of a developer’s code. The robustness of a builder’s wall. The speed of an F1 driver’s lap.
But you need to allow for human evaluation when developing leaders. Sure, set them goals or objectives. But be ready on occasion for them to do better things and miss the objective. Your best team members follow the vision, not the metric.