Acceptance rate is a vanity metric. ROI is what shipped.
The number GitHub hands you is acceptance rate: the share of Copilot suggestions a developer tabbed into a file. It is easy to report and easy to inflate, and it tells a leadership team almost nothing about return on investment. Accepted code that gets rewritten in review, reverted after a bug, or quietly deleted next sprint is a cost, not a gain.
Real Copilot ROI is quality-adjusted velocity: output that passes review, stays merged and reaches production, measured against seat licenses and token spend. FeatureFactory scores Copilot-assisted changes on the signals that predict durability, including rework rate, revert risk, review depth and test coverage deltas, so a fast quarter is never quietly a fragile one. Dig into the mechanics in our AI vs. human code quality guide.
The point is not to distrust Copilot. It is to make its impact measurable and defensible so you can renew, expand or cut seats with evidence instead of a vendor dashboard. See how it works on the measure product page.