It's very hard to measure this accurately at scale.
If you create metrics, they will be gamed. The people that succeed, then, are not necessarily those with the most merit, but those who are best at manipulating their metrics.
We started measuring progress this month by measuring how many percent of last week's planned tasks were completed, and it's already showing.
Everyone is reporting 100 % which means they're probably doing three days worth of work in one work week to keep the number up.
One product owner showed 12 tasks out of 57 being completed and still gave out a 100 per cent completion rate because he retroactively rated those 12 as critical and the rest as unimportant.
If you create metrics, they will be gamed. The people that succeed, then, are not necessarily those with the most merit, but those who are best at manipulating their metrics.