wbh sez: At some point I'll probably roll this into embedded tooltips in the blog post, but that will be time consuming so until then:
A blog post by CEO Travis Kimmel, describes the "five key metrics" that used behind the scenes: lead time [commits/PRs]; code churn [lines of code]; impact [lines of code]; active days [commits]; and efficiency [lines of code].
A blog post by CEO Jeff Haynie breaks down five metrics for CEOs, all of which are based off performance relative to Jira's expectations. They are backlog change [issues], throughput [issues], cycle time [issues], workload balance [issues], defect ratio [issues].
A blog post by Head of Product Marketing Sasha Rezvina provides the most detailed and comprehensive summary of which metrics are considered most important by Code Climate. These are listed as: coding days [commits], pushes per day [commits], time to open [commits/PRs], rework [lines of code], pull request throughput [PRs], and cycle time [commits/PRs].