Estimated outcome probability. A likely winner can still be overpriced.
← Decision briefsMLB · Sep 13, 11:20 AM PDT FORECASTChicago Cubs RELIABILITY4/4 model reports MARKET VALUENot established
Pittsburgh Pirates vs Chicago Cubs
60.1%Chicago Cubs
LOCKED Sep 13, 10:30 AM PDT4/4 independent models select Chicago Cubs; all four oriented probabilities average 60.13%.
15 reported evidence limits. Agreement alone does not establish accuracy.
A probability difference alone does not account for forecast error, fees, spread, or available liquidity.
Why the models lean this way
These are reasons recorded by the models. They are not independently verified facts or measured causes of a probability change.
- Claude: Chicago's 30-day offense (6.00 R/G, +1.148 run differential per game) sharply outpaces Pittsburgh's (3.731 R/G, 0.0 differential)
- Gemini: Cubs' strong recent offense (6.0 runs/game last 30 days)
- Grok: Cubs superior season and recent offensive output
- GPT: Cubs have the better overall record: 93-79 vs Pirates 85-86
Read all four model reports
Claude · Chicago Cubs · 63.0%
Chicago is the stronger club on every team-level input in the package: a 93-79 record versus Pittsburgh's 85-86, and a large offensive gap over the last 30 days (6.00 runs per game and +1.148 run differential per game for the Cubs versus 3.731 runs per game and 0.0 differential for the Pirates). The 7-day window points the same direction (5.167 vs 3.5 runs per game). Add standard home-field advantage and a park run factor of 1.064, which favors the side that scores more consistently. The main counterweight is pitching: Matthew Boyd's 30-day ERA of 5.46 is worse than his 4.03 season mark, while Bubba Chandler's recent form (4.21 ERA, 1.17 WHIP) is a touch better than his season line (4.25 ERA, 1.34 WHIP), so the starter edge is essentially neutral or slightly Pittsburgh in recent form. Bullpen availability is nearly identical (73 home vs 75 away), and a weather run factor of 0.952 modestl
anthropic/claude-opus-5 · Sep 13, 8:45 AM PDTGemini · Chicago Cubs · 58.5%
The Chicago Cubs hold a significant offensive advantage, averaging 6.0 runs per game over the last 30 days compared to the Pirates' 3.731. While Cubs starter Matthew Boyd has struggled recently with a 5.46 ERA over his last 30 days, the Cubs' potent offense and overall superior season record (93-79 vs 85-86) give them the edge at home.
google/gemini-3.1-pro-preview · Sep 13, 8:45 AM PDTGrok · Chicago Cubs · 57.0%
Cubs hold a stronger overall record (93-79 vs 85-86) and show markedly better recent offense (6.0 runs per game over 27 games vs 3.731 for Pirates). Home status and confirmed lineups add slight edge despite comparable bullpen availability. Starters present mixed signals with Boyd's recent ERA elevated at 5.46.
xai/grok-4.3 · Sep 13, 8:45 AM PDTGPT · Chicago Cubs · 62.0%
Chicago has the stronger overall case from the supplied evidence. The Cubs have the better season record (93-79 vs 85-86), are at home, and their offense has been clearly better both recently and over the last 30 days. Over the last 30 days, Chicago is scoring 6.0 runs per game compared with Pittsburgh's 3.731, and even over the last 7 days the Cubs hold an edge at 5.167 vs 3.5. Starting pitching is fairly close: Matthew Boyd has slightly better full-season ERA/WHIP than Bubba Chandler, while Chandler has the better recent-30 ERA. That pitching comparison does not outweigh Chicago's larger offensive edge and home-field advantage. Bullpen availability is nearly even, so it does not materially shift the call.
openai/gpt-5.4 · Sep 13, 8:45 AM PDTWhat remains uncertain
- Probable pitchers are listed but not guaranteed; a late scratch would materially change this read.
- Lineup status is reported as confirmed, yet there are 2 away and 4 home lineup changes noted, and the package does not identify which players are in or out, so I cannot assess whet
- Run differential per game is reported as 0.0 for Pittsburgh in both windows and for the Cubs in the 7-day window, which looks like a partially unpopulated field and limits how much
- No bullpen quality metrics, only availability percentages; no handedness splits, no batter-versus-pitcher data, and no head-to-head history.
- Sample sizes are small: 6 games in the 7-day window and 26-27 games in the 30-day window.
- No odds or market information was supplied and none was inferred; this is a standalone probability estimate, not a value assessment.
- Matthew Boyd's recent high ERA introduces variance and could allow the Pirates to capitalize early
- The weather run factor of 0.952 suggests slightly suppressed scoring conditions, which could mitigate the Cubs' offensive advantage
What to watch next
Official result recorded. Review the original forecast and sources below.
Open the event and source context →What changed before the lock
- First recorded forecast
The pre-event probability state was locked atomically and is immutable.
Record hash
2d75449381a739b08ef7ced41f811a0c9efc3f83ec42927e95f500b9483b5e8e - First recorded forecast
First prospective probability state captured for this source and competition.
Record hash
c747765b6ac61368a2e7ae59ac5d10ec5fb0462ba56b56c9ed32a206499c6e09
Reasons are shown as they were recorded. The ledger does not establish that a specific fact caused a probability change.
The saved method comparison
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Recorded outcome: Pittsburgh Pirates 4, Chicago Cubs 3
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