ACL 2026 — Industry Track ·
From TextBlob to LLM Agents: Sentiment Model Selection for B2B Technical Support with CSAT Ground Truth
Pedro Vidigal · pages 1774–1782 · San Diego, California, USA
A five-year case study of sentiment model selection for customer satisfaction (CSAT) prediction in B2B technical support. The evaluation uses the complete population of CSAT-rated tickets from an enterprise software company: over 500 tickets comprising ~2,500 customer comments from 100+ organizations over five years. 17 approaches across 5 paradigms, plus 11 fine-tuning experiments.
Findings
- A dedicated single-task LLM agent reduces neutral bias from 69% to 22%, improving MCC from -0.018 to 0.347 (p<0.001).
- Consistent with the Alignment Tax: Claude Opus 4.6 exhibits 41% neutral predictions and lower recall than its budget model Haiku 4.5 (p=0.003).
- ~38% of dissatisfied customers are undetectable by all 12 LLMs, because administrative requests lack emotional language.
- Gemini 3 Flash achieves the best MCC (0.347) at $0.60/1K, over 100x cheaper than Claude Opus.
- All 11 fine-tuning experiments achieved MCC <= 0.
- doi:10.18653/v1/2026.acl-industry.121
- vidigal-2026-textblob