The week’s largest qualified MLB leader flip

Pittsburgh led early; Cleveland finished at 51.2% after a 10.38-probability-point leader swing.

Pirates–Guardians pre-game probability trace with percentage and Eastern-time axes, a neutral 50% reference line, contextual lineup-post timing, Cleveland’s first observed lead at 11:10 AM, the 1:30 PM final observation, and the 1:40 PM first-pitch boundary.
Pirates at Guardians · July 19 · Pre-game win probability · Transformed aggregate market data

What changed

Reading the trace.

Across 99 scheduled MLB games in the editorial window, Pirates–Guardians produced the largest qualified leader flip. Pittsburgh held 54.03% at the first qualified observation. Cleveland first appeared ahead at 11:10 AM Eastern and held 51.16% at the final included check at 1:30 PM.

The 10.38-probability-point leader swing spans 140 observations, up to 11 reporting books, and one observed flip. Every observation at or after the official 1:40 PM Eastern first-pitch boundary was excluded.

Both clubs posted their starting lineups shortly before Cleveland’s first observed lead. That timing is useful context, not a causal explanation. The broader schedule was unusual: Friday’s game was postponed because of wildfire-smoke air quality, moved into a Saturday split doubleheader, and followed by the Sunday finale.

Context sources

Scope and method

Aggregate prices were normalized into market-implied win probabilities. The trace begins with the first coverage-qualified observation and ends at the final pre-game check; public lineup and schedule events are timing context, not causal claims.

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