To clarify, the tool is not meant to measure "success". In that case, you are absolutely right, it cannot be used for that. And I don't think a tool can measure those things.
The tool only is only meant to track important producitivty metrics. PerfPerf is here to check that there isn't someone "playing the game" and doing the bare minimum. AND to praise the ones doing more!
Example: When someone on a team, always approves PR's without never requesting changes. If that behavior is not standard in the team, it's gonna be flagged if happening for a full month.
Example2: Someone on the team, review only 20% of the PRs when requested as reviewer compared to the average of that team that review 60%. that's also gonna be flagged for review.
Let me know if that makes sense.