I really don't think you can measure output and understand value for anyone but the most junior of engineers who basically need to churn out code to be valuable in the short term (and that's for those who do not have a questioning mindset to understand why they need to build what they are asked to). 6 months in and it becomes useless even for them as they acquire domain knowledge.
To me the article reads that simplistic metrics do no accurately assess performance of employees.
Managers need to work out what their reports are working on, and base an opinion on performance using more than just "number of tasks closed" etc.
by creating these simplistic metrics, it means that the management chain has a false sense of what make the company tick. That confidence is the rot, not the poor performers. Simply because they do not actually know who the poor performers are.