This is really interesting, thank you.

It's one of the only clear-metric breakdowns that actually makes sense in light of my programming experiences. I'm hesitant about the idea of using it as a management tool (easy to game, and high commit count or even 'high impact' isn't proof of quality). And, as some other people noted, it's quite role-specific - a performance engineer's commit count won't be comparable to a line engineer.

But as a personal insight, or a mentoring tip? This seems excellent. I know I want to write good code, I'm not going to game my personal metrics, so a clear guideline like "break up code more" is a great thing to have.