Seattle Mariners vs. Houston Astros
Crossbook compares what two exchanges, Polymarket and Kalshi, charge for the same event, and publishes a permanent scored record of its own forecasts under published rules.
Tracked on one venue, with Crossbook's own call on the record.
This market has settled and is no longer listed, so there is no current price to show. What Crossbook called, and when, is below.
Crossbook forecast
- 15.0%against a market price of 8.5% at the timeYESNOT SCORED
Logged 15 Aug 2026, 02:28 UTC
Not scored: this was logged after the event had already started, which Crossbook’s forecast window failed to catch because the venue published a closing date that included a dispute buffer. It counts toward nothing. Why.
- A single-game Mariners-vs-Astros market should price the weaker side at 25-45%; the observed 8.5% with $333k volume is far outside that band, so this is almost certainly NOT a simple game moneyline.
- The most plausible interpretation is a season-long head-to-head (e.g., season series winner or who finishes higher in the AL West), where by mid-August the outcome can be largely decided; 8.5% then implies the Mariners side is nearly eliminated, which is consistent with the efficient-looking volume.
- My independent single-game base rate (~0.35-0.40) and the market price diverge so sharply that the divergence itself is the key signal: either the market resolves on a longer-horizon question or I lack information (injuries, standings, pitchers) that justifies an extreme price; in both cases I shade well below the naive base rate but stay above the market due to residual uncertainty and late-season variance.
- Without verified 2026 standings/rotation data, I cannot justify high confidence; I anchor near the market with a modest upward adjustment for tail outcomes over a 7-day window.
What would change it: Confirmation of the exact resolution criteria (single game vs. season series/standings) and current AL West standings would move this estimate by 20+ points in either direction.
Settlement source
Context
This market has settled. The page is kept as a record of what the market said while the question was open, and of what Crossbook called.
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