Several companies operating in the North Sea and elsewhere have utilized a metric based on a corrective action classification system. Historically, that metric was developed by this author (Veley, 2002) and it initially appeared to be a valuable leading indicator for management purposes. It is a semi-quantitative indication of the strength of corrective actions, and that should be directly linked to the likelihood of problems recurring; the stronger the corrective action the less likely the accident is to repeat. However, after trial applications it became clear that when this metric was used to define performance goals it had unanticipated consequences that cumulatively and insidiously caused more damage than the accidents it was intended to prevent. This paper will discuss those unintended consequences and explain why, in common situations, permanent corrective actions can produce harm, while temporary actions produce improvements. Category Matching is an upgrade of that original metric and eliminates harmful unintended consequences of corrective action classifications used alone.