If they are meeting the metrics set to judge their performance how are they bad employees? If the metrics don't properly measure whether the job is being done then change the metrics.
Nobody has ever come up with a good set of objective metrics to judge software engineer performance. So the best we have is still the subjective opinions of your managers and peers.
Imagine I sent a manuscript to a publishing house and they rejected it for being bad. I wouldn't expect they got to that conclusion by comparing it to a set of metrics, I would assume they have people in authority whose judgement is the decider on whether something is "good" or "bad".
Human endeavors sometimes fail to live up to expectations.
For workers who work with their heads, "metrics" is a fantasy. How do you measure a better writer?
How do you measure a better writer? It depends on what the purpose of the writing is. If it is an author directly selling books then you measure by books sold. If it is an online publication you can conduct surveys to determine the impact of a particular writer on subscription or view rates. If it is a techincal writer doing product documentation you can measure based upon meeting schedule, number of defects and by conducting customer surveys.
> If it is an author directly selling books then you measure by books sold.
This is a fairly lousy metric. It depends enormously on the marketing campaign and the ability of salesmen to sell it.
For example, I read an article about the author of the "Slow Horses" book. It languished for years selling at a rate that was indistinguishable from zero. Then some journalist read it, wrote a glowing review of it, and it took off. Now it's a best seller, with sequels, and a miniseries.