First Win / Free research
Sharp lines. Tough returns.
Picking winners is only half the bet. The price decides what those wins are worth.
The quick take
The odds held up. The returns didn’t.
Closing odds lined up closely with results across the probability groups we tested. But backing every team at the sampled prices returned -3.55%. Accurate odds don’t automatically make a profitable bet: the sportsbook’s margin is built into the price.
The numbers behind it
- Team-side bets studied
- 23,992
- 11,996 games. Both sides of each game.
- Return per unit risked
- -3.55%
- 95% interval: -3.9% to -3.2%.
- Price ranges that lost
- 9 / 10
- Fixed ranges, chosen before checking results.
Follow the evidence
Where the money went
Each bar is a price range. Left of zero means a loss. The thin range shows uncertainty.
That small positive bar? +126 to +150 returned +0.42%, with a 95% interval of -3.9% to +4.8%. That includes a loss. It isn’t evidence of a reliable edge.
What this means for your bet
- Check the price, not just the pick. Judge a model at odds you could actually take, with the margin included.
- Look past the best-looking row. A positive result needs uncertainty checks and evidence across seasons before it deserves your confidence.
The catch: This is historical MLB closing-price data at average eligible-book prices. It doesn’t test a specific betting strategy, earlier prices, or the prices available in your account.
Want to check our work?
The full evidence
See every price range and return
| Bucket | n | Avg price | Expected | Actual | Gap | 95% CI on gap | ROI | Seasons + |
|---|---|---|---|---|---|---|---|---|
| +201 or longer | 928 | +235 | 29.04% | 27.16% | -1.89 pp | -4.6% to +1.0%spans 0 | -9.40% | 1/5 |
| +151 to +200 | 2,318 | +172 | 35.66% | 36.07% | +0.40 pp | -1.6% to +2.3%spans 0 | -2.56% | 1/5 |
| +126 to +150 | 2,828 | +138 | 40.64% | 42.26% | +1.61 pp | -0.2% to +3.5%spans 0 | +0.42% | 2/5 |
| +101 to +125 | 4,098 | +113 | 45.32% | 44.31% | -1.00 pp | -2.5% to +0.5%spans 0 | -5.69% | 0/5 |
| even to -120 | 4,198 | -110 | 50.32% | 50.52% | +0.21 pp | -0.3% to +0.7%spans 0 | -3.29% | 0/5 |
| -121 to -140 | 2,626 | -130 | 54.46% | 56.02% | +1.56 pp | -0.4% to +3.5%spans 0 | -0.80% | 2/5 |
| -141 to -160 | 2,297 | -148 | 57.63% | 56.73% | -0.90 pp | -2.9% to +1.2%spans 0 | -5.01% | 1/5 |
| -161 to -200 | 2,782 | -177 | 61.62% | 59.92% | -1.70 pp | -3.5% to +0.2%spans 0 | -6.18% | 0/5 |
| -201 to -250 | 1,211 | -224 | 66.60% | 68.13% | +1.53 pp | -1.1% to +4.2%spans 0 | -1.44% | 4/5 |
| -251 or shorter | 706 | -292 | 71.71% | 72.24% | +0.53 pp | -2.9% to +3.7%spans 0 | -2.98% | 2/5 |
Check how closely the odds matched results
9 of 9 probability bands have a 95% gap interval that includes zero. That means we couldn’t distinguish their forecasts from perfect calibration at this sample size. It doesn’t prove the forecasts were exact.
| Bucket | n | Avg price | Expected | Actual | Gap | 95% CI on gap | ROI | Seasons + |
|---|---|---|---|---|---|---|---|---|
| <35% | 1,753 | +213 | 31.16% | 29.49% | -1.67 pp | -3.9% to +0.5%spans 0 | -8.59% | 1/5 |
| 35-40% | 2,454 | +156 | 37.77% | 39.20% | +1.43 pp | -0.5% to +3.3%spans 0 | +0.22% | 3/5 |
| 40-45% | 3,647 | +127 | 42.60% | 43.13% | +0.53 pp | -1.1% to +2.1%spans 0 | -2.15% | 3/5 |
| 45-50% | 4,142 | +103 | 47.52% | 47.47% | -0.05 pp | -1.6% to +1.4%spans 0 | -3.84% | 2/5 |
| 50-55% | 4,142 | -120 | 52.48% | 52.53% | +0.05 pp | -1.4% to +1.6%spans 0 | -3.62% | 3/5 |
| 55-60% | 3,647 | -147 | 57.40% | 56.87% | -0.53 pp | -2.1% to +1.1%spans 0 | -4.32% | 2/5 |
| 60-65% | 2,454 | -181 | 62.23% | 60.80% | -1.43 pp | -3.3% to +0.5%spans 0 | -5.71% | 2/5 |
| 65-70% | 1,209 | -231 | 67.25% | 69.31% | +2.06 pp | -0.5% to +4.6%spans 0 | -0.67% | 4/5 |
| 70%+ | 544 | -303 | 72.37% | 73.16% | +0.79 pp | -3.1% to +4.5%spans 0 | -2.61% | 3/5 |
Check the results season by season
| Bucket | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|
| +201 or longer | -0.7% | +5.6% | -19.7% | -11.0% | -28.9% |
| +151 to +200 | -4.1% | -11.4% | +9.4% | -3.2% | -1.6% |
| +126 to +150 | -3.3% | -2.9% | +5.4% | -5.1% | +8.7% |
| +101 to +125 | -5.9% | -9.8% | -10.7% | -2.0% | -1.2% |
| even to -120 | -2.5% | -4.3% | -2.6% | -3.5% | -3.7% |
| -121 to -140 | -4.4% | +2.9% | +5.1% | -0.9% | -6.4% |
| -141 to -160 | +4.2% | -0.9% | -7.3% | -12.1% | -8.4% |
| -161 to -200 | -7.3% | -2.6% | -8.9% | -2.0% | -10.8% |
| -201 to -250 | +0.8% | +0.7% | -11.1% | +1.3% | +1.9% |
| -251 or shorter | -8.5% | -6.2% | +3.9% | -3.4% | +1.0% |
-201 to -250 was profitable in 4 of 5 seasons, yet returned -1.44% overall. In 2023, it returned -11.1%. Counting winning seasons misses how big the losses were.
Read the method, definitions and limits
How this was measured
Every number derives from one definition, frozen before any result was computed. The spec hash is in the provenance panel at the foot of this page.
- Closing price. The latest complete, eligible pre-game bookmaker observation no more than 30 minutes before scheduled first pitch. A book’s stale quote is not a closing price.
- Consensus. Each book’s own two-way prices are de-vigged first, then eligible books are equal-weighted. Order matters: averaging vigged prices and de-vigging afterwards bakes in the spread of book margins.
- Sample. 2021, 2022, 2023, 2024, 2025 regular season, all eligible books, typically 8–10 per game. 2020 is reported separately below.
- Returns. One unit risked per selection, each game weighted equally regardless of how many books priced it.
- Buckets were fixed in advance. No edge was moved after seeing a result, and no bucket was merged or split.
- Event-selections
- 23,992
- One row per team side per game
- Return on risk
- -3.55%
- -852.46u at executable prices
- Vig paid
- +1.87 pp
- Per side, raw against no-vig
Definitions
Three numbers get confused constantly in public betting analysis, and most bad conclusions come from mixing them up. These are the terms used on this page.
- Executable odds (quoted price)
- The American price you could actually have bet at. Risking 150 to win 100 is −150. Every return here is computed against these prices, because they are what a bettor transacts at.
- Raw implied probability
- An executable price converted straight to a probability with no adjustment. −150 becomes 60.0%. The bookmaker’s margin is still inside it, so the two sides of a game sum to more than 100% and this number includes the bookmaker margin; it is not a margin-free probability estimate.
- Vig (also “juice”, “overround”)
- The bookmaker’s margin, built into both sides of the market. Measured as how far the two sides’ raw implied probabilities exceed 100%. In this sample they sum to about 103.7%, an overround of 3.7%.
- Vig paid per side
- The same margin for a single bet: how far its raw implied probability sits above its no-vig probability, in percentage points. Sample average +1.87 pp. This is a probability-point measure, not a percentage loss on stake.
- No-vig probability, shown as “Market expected”
- The market’s genuine estimate once the margin is stripped out. Each book’s own two-way prices are de-vigged proportionally, then eligible books are equal-weighted. Calibration is tested against this, because it is what the market actually believes. It is never used to compute returns.
- Actual win rate
- The share of selections in a group that won: wins divided by n.
- Calibration gap (residual)
- Actual win rate minus market-expected probability, in percentage points. Positive means the selection won more often than the market expected. Zero is perfect calibration.
- Return on risk (ROI)
- Profit or loss per unit risked, betting one unit on every selection in the group at its executable price. -3.55% means losing 3.55 units per 100 risked.
- Units, total units
- Cumulative profit or loss in bet units, one unit risked per selection. -852.46u means the strategy finished that far down.
- Event-selection
- One side of one game, and the unit of analysis here. A game contributes two, home and away. Roughly 11,996 games gives 23,992 event-selections.
- Closing price
- The latest complete, eligible pre-game quote no more than 30 minutes before scheduled first pitch. The last eligible quote in this dataset.
- Consensus
- The equal-weighted average across eligible books, taken after each book’s own prices have been de-vigged individually.
- Odds bucket
- A fixed range of executable prices. Ranges were frozen before any result was computed.
- Probability band
- A fixed range of no-vig probabilities. Bands split at 50%, so a price and its complement can never land in the same band.
- 95% confidence interval
- A range expressing sampling uncertainty. All three come from the same deterministic event-clustered bootstrap, with the game as the resampling unit so two selections from one game keep their dependence. An interval containing zero means the effect cannot be distinguished from no effect at this sample size.
- “Spans 0”
- A tag marking a calibration gap whose interval contains zero: not distinguishable from perfect calibration.
- “Seasons +”
- How many individual seasons showed a positive value, out of those reported: return for odds buckets, residual for probability bands. A check on whether a pooled result rests on one unusual season.
Limits of the study
Closing prices only; no live markets, props or prediction model. Returns use the mean eligible-book price, not a guaranteed fill. A different available price would change the return.
Both sides of each game are included. Uncertainty is clustered by game so those paired observations aren’t treated as independent. The probability bands split at 50%, keeping mirrored sides apart.
Fixed price ranges reduce the temptation to cherry-pick. They don’t establish how a future strategy will perform.
See the separate 2020 sample
Appendix: 2020
The shortened season and thinner book coverage are excluded from the headline sample.
1,556 team-side bets. Return: -2.93%.
Methodology, version and provenance
Intervals are 95% percentile intervals from a deterministic event-clustered bootstrap: 2,000 iterations, fixed seed, the game as resampling unit, so multiple selections from one game keep their observed dependence. Events are ordered canonically before the random stream is consumed, so an interval does not depend on input row order. The parent hash above is the original v1 freeze, retained as provenance; v1.0.1 changes only the uncertainty method, never a point estimate. These figures are a sealed artifact produced once against the fact build above. They are served read-only and are not recomputed on request, so a published number cannot drift when the corpus is rebuilt.
Ask your own question of this data
Ask First Win uses the same research engine behind these figures and shows the exact scope and evidence for every answer.
Ask your own questionGet new sports-market research when we publish
New research, straight to your inbox. No picks, no promotions. Our public studies stay free to read without an account.
First Win Pro
Keep asking better questions.
Short research briefs. The numbers behind them. Full methods when you want to dig deeper.
Explore Pro