ESG metrics, which are central to sustainable finance, face increasing scrutiny for their accuracy and representativeness. Concerns arise from retrospective score adjustments and data aggregation, risking misrepresentation of company performance. The European Parliament recently proposed a Regulation on ESG rating transparency, stressing the issue's urgency. In this context, we highlight that methodological choices can artificially inflate scores of top-ranked companies with new, lower-performing entrants, masking real progress through peer competition. Our 2012-2021 analysis in three key sectors shows that on average less than 45% of total pillar score variation is due to company disclosures. Replacing Refinitiv's percentile rankings with a simpler ‘‘performance ratio" methodology could mitigate these issues, offering more representative scores. Our performance ratio shows significant correlation with Refinitiv's approach but is less influenced by new entrants and peer comparisons, remaining robust to outliers.