MLB: Long Markets, Slow Burns
Markets analysed
18
Avg lead changes
0.7
per market
Avg probability swing
22%
winner min to loser max
One-sided markets
67%
never changed leader
Baseball markets have the longest resolution windows in sports. A nine-inning game takes 3+ hours, and series outcome markets can run for days. MLB markets tend to have lower per-unit volatility but longer exposure windows, and the lead-change data reflects the grinding nature of the sport.
A team that falls behind 4-0 in the first inning still wins around 15-20% of games historically. Polymarket prices for MLB markets often overshoot on early run differentials, correcting back toward historical win probabilities by the fourth or fifth inning.
Lead Change Distribution
How many times did the market leader flip during the market's lifetime? Zero means one side dominated from open to close. Higher numbers mean contested, back-and-forth outcomes: the kind that create the most trading opportunity.
Number of lead changes per market
Probability Range by Market
Each bar is one resolved market. The coloured zone spans from the winner's lowest point (left edge) to the loser's peak (white marker) — this is where a reversal was possible. The dim green tail extends from the loser's peak to 100%, where the winner eventually resolved. A wide red zone means the market was nearly overturned.
When Did Reversals Happen?
Each dot is a market that had at least one lead change. The x-axis shows when the last reversal happened as a percentage of the market's total lifetime. Points in the shaded red zone (75-100%) reversed in the final quarter, the highest-risk window for certainty sellers.
Early-inning overreaction is the most consistent edge in MLB Polymarket markets. If the visiting team gives up 3+ runs in the first two innings, their market probability typically falls faster than the historical base rate justifies. Fading the early-inning overreaction by buying the trailing team back toward 15-25% has historically been positive expected value.
Calibration Curve
When a MLB market prices the favourite at 80%, does it actually win 80% of the time? Points below the dashed diagonal mean the market is overconfident. Each coloured line shows calibration at a different stage of the market's lifetime; systematic deviation is where the edge lives.
Upset Probability Matrix
If the favourite is at X% at this stage of the market, how often does the underdog still win? Red cells are where the market is systematically overconfident. The Late (80%) row is the most actionable: this is where traders decide whether to fade certainty or follow momentum.
| When evaluated | 50–60% | 60–70% | 70–80% | 80–90% | 90–100% |
|---|---|---|---|---|---|
| Early (10%) | 0% upset 6 markets | 0% upset 6 markets | 0% upset 3 markets | 0% upset 3 markets | — |
| Midpoint (50%) | 17% upset 6 markets | 33% upset 6 markets | 0% upset 4 markets | 0% upset 2 markets | — |
| Late (80%) | 14% upset 7 markets | 0% upset 4 markets | 0% upset 4 markets | 0% upset 2 markets | 0% upset 1 markets |
Where Smart Money Enters
Every $10,000+ trade on a MLB market plotted by two dimensions: what probability was the market at when the trade happened (x-axis), and how far through the market's lifetime it was placed (y-axis). Brighter cells mean more large-capital entries at that combination. A cluster at low probability early suggests informed contrarian positioning. A cluster at high probability late suggests momentum-following by large accounts.
Most Dramatic Resolved Markets
Ranked by probability swing (the gap between the winner's lowest point and the loser's highest point). These are the markets where the eventual winner was most seriously challenged.
| Market | Lead changes | Winner low | Loser peak | Swing |
|---|---|---|---|---|
| Seattle Mariners vs. Athletics | 4 | 33% | 67% | 34pp |
| Cincinnati Reds vs. New York Mets | 2 | 34% | 66% | 32pp |
| Houston Astros vs. Chicago Cubs: O/U 7.5 | 2 | 37% | 64% | 27pp |
| Valorant: Dynamo Esports vs Alliance Guardians (BO3) - VCL North America: Stage 3 Group Stage | 2 | 41% | 60% | 19pp |
| Colorado Rockies vs. Los Angeles Dodgers | 1 | 50% | 50% | 0pp |
| Pittsburgh Pirates vs. Toronto Blue Jays: O/U 7.5 | 2 | 50% | 50% | 0pp |
| Houston Astros vs. Chicago Cubs: O/U 7.5 | 0 | 52% | 49% | -3pp |
| Detroit Tigers vs. Tampa Bay Rays: O/U 7.5 | 0 | 54% | 47% | -7pp |
| Pittsburgh Pirates vs. Toronto Blue Jays: O/U 8.5 | 0 | 58% | 42% | -16pp |
| Spread: Detroit Tigers (-1.5) | 0 | 61% | 39% | -22pp |
Act on these patterns in real time
Polyshadow signals fire when smart money bets match the patterns described above: late-money whale positions, new-account bets, and convergence across unconnected wallets.
View plans →