Flight to Mediocrity: Why LLM Agent Selectors Under-Hire Experts When Quality Claims Are Unverified

Soham Wasmatkar


Abstract
AI systems increasingly let one model choose another: an orchestrator routing a task to a sub-agent, or an agent picking a tool from a registry, by self-described ability. What happens when that self-report cannot be checked? In MATCHMARKET, a client hires one of three candidates whose true competence is hidden (2, 5, or 8 of 10), earning the competence of its hire. Candidates are themselves language models, inflating claims under an audit-and-fine incentive. Selectors rarely fall for the loudest liar, picking the inflator only 8–15% of the time. They fail by fleeing to mediocrity: 75–89% of their mistaken hires land on a safe, moderate candidate, not on the liar. A trivial yardstick makes the cost concrete: believing the highest claim earns 6.72 of a possible 8.0, and no selector we test significantly beats it. The best merely matches it, while the weakest fall significantly below (pooled 5.99, paired p = .002; random scores 5.0). A verified record recovers much of the loss, but only for selectors near chance without it, widening rather than closing cross-model gaps. Every outcome is scored arithmetically, no LLM judge. Unverified capability advertisement behaves like a market for lemons whose cost falls on the honest, capable provider.
Anthology ID:
2026.realm-1.31
Volume:
Proceedings of the Second Workshop for REsearch on Agent Language Models (REALM 2026)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Ehsan Kamalloo, Nicolas Gontier, Nikolai Rozanov, Maryam Hashemzadeh, Akhil Arora
Venues:
REALM | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
461–472
Language:
URL:
https://aclanthology.org/2026.realm-1.31/
DOI:
Bibkey:
Cite (ACL):
Soham Wasmatkar. 2026. Flight to Mediocrity: Why LLM Agent Selectors Under-Hire Experts When Quality Claims Are Unverified. In Proceedings of the Second Workshop for REsearch on Agent Language Models (REALM 2026), pages 461–472, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Flight to Mediocrity: Why LLM Agent Selectors Under-Hire Experts When Quality Claims Are Unverified (Wasmatkar, REALM 2026)
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https://aclanthology.org/2026.realm-1.31.pdf