Lines or amount of code written is a terrible, and easily gamed metric.
Some of the very best engineers write the fewest lines of code, often making fewer yet better abstractions that fulfill more business use cases more simply. They might also help others write less code.
Some of the most prolific coders are great. And some are terrible. The challenge is discerning the two. Coaching a prolific yet bad coder to slow down can be as challenging as coaching up a slower / not yet confident coder. And the slower coder will do vastly less damage in the interim.
I understand this as theoretical possibility, and it could lead you astray if you're trying to tell a 40% developer from a 60% developer... but in practice I have never met a superstar IC who doesn't also ship a ton of code (even while they help out others). If you fire the 10% of ICs who push the least code, to within a rounding error you're extremely unlikely to regret it.
It's strange to see this confusion when it comes to software. Any other discipline and you wouldn't say engineers that don't do any engineering are the best engineers.
Some of the very best engineers write the fewest lines of code, often making fewer yet better abstractions that fulfill more business use cases more simply. They might also help others write less code.
Some of the most prolific coders are great. And some are terrible. The challenge is discerning the two. Coaching a prolific yet bad coder to slow down can be as challenging as coaching up a slower / not yet confident coder. And the slower coder will do vastly less damage in the interim.