To be really clear, Fable is Opus. Anthropic finished a new pre-training run, Opus-sized models got enough of a jump they could have released Fable as Opus 5..

To be really clear, Fable is Opus. Anthropic finished a new pre-training run, Opus-sized models got enough of a jump they could have released Fable as Opus 5... but the economics of Opus models weren't where they wanted. Being the masters of distribution that they are, instead of announcing a massive price hike, they just introduced a new tier and promoted Sonnet-sized models to Opus. That's why every Opus after 4.6 has had such mixed feedback: smaller model with more RL can only make up so much ground, especially on vibes (which are hard-to-impossible to build a reward for) (I mention all of this because if they'd just released Opus 5, no one would be asking "why is it a few months later everyone caught up to the latest release"... that's always how it works)