README.md

---
license: cc-by-4.0
language:
  - en
pretty_name: SmartStake MLB Lineup Reactions (2026)
tags:
  - sports-betting
  - sports-analytics
  - mlb
  - baseball
  - odds
  - player-props
  - lineups
size_categories:
  - 10M<n<100M
task_categories:
  - time-series-forecasting
configs:
  - config_name: default
    data_files:
      - split: train
        path: "mon=*/*.parquet"
---

# SmartStake MLB Lineup Reactions (2026)

Full-resolution sportsbook odds movements around every Underdog MLB lineup post of
the 2026 season, for the six player-prop markets a batting-order change moves. Every
row is one book's price for one selection at one moment, in a window around a lineup
drop. This is the raw material behind the study
["MLB Lineup Drops"](https://smartstake.app/learn/mlb-lineup-drops), a companion to
[SmartStake MLB Player Prop Odds and Results](https://huggingface.co/datasets/SmartStake/mlb-player-props).

## Coverage

- **Events:** 2,456 Underdog MLB lineup posts with odds, 25 March through 17 July
  2026. Each post is one team's lineup; the All-Star Game is excluded.
- **Window:** −5 to +20 minutes around each post (`offset_sec`), so both the
  pre-drop baseline and the full reaction are present.
- **Markets:** total bases, hits, RBIs, runs, hits + runs + RBIs, strikeouts.
- **Books:** 73 sportsbooks, exchanges, prediction markets, and DFS pick'em products.
- **Rows:** ~85 million (one book's price for one selection at one moment).
- **Coverage gap:** the odds archive was down on 26 May and from 20 to 29 June 2026,
  so lineup posts on those days (about 11% of the season's posts) have no odds and
  are absent.

## Schema

| column | type | description |
|---|---|---|
| `event_id` | string | One lineup post: `team~tweet_ts`. Group on this. |
| `team` | string | The team whose lineup posted. |
| `tweet_ts` | timestamp | When Underdog posted the lineup (UTC). |
| `game_id` | string | Stable per-game identity. |
| `player` | string | Canonical player name. |
| `player_id` | int64 | Stable player id (consistent across books). |
| `market` | string | `bases`, `hits`, `rbis`, `runs`, `hits + runs + rbis`, or `strikeouts`. |
| `line` | double | The over/under number for this selection. |
| `side` | string | `over` or `under`. |
| `book` | string | Sportsbook / exchange / DFS product. |
| `engine` | string | Pricing engine; collapses shared-brain skins (see notes). |
| `ts` | timestamp | When the quote was live (UTC), full resolution. |
| `offset_sec` | int | `ts − tweet_ts`, in seconds. Negative is before the post. |
| `odds` | double | Decimal odds. Null for DFS pick'em products (see notes). |
| `is_suspended` | bool | `true` when `odds ≤ 1.02`: the market was pulled, not a real price. |
| `is_alt` | bool | `true` for an alternate (non-main) line. |

## Notes and caveats

- **Suspensions are kept but flagged.** A book (Pinnacle especially) often pulls a
  market before reposting a new number; those ticks carry `odds ≤ 1.02` and
  `is_suspended = true`. Filter them out before treating `odds` as a price.
- **Skins are collapsed by `engine`.** Books that share one pricing brain get one
  `engine` value so a single book is not counted several times: `betmgm` covers
  betmgm, bwin, and Sports Interaction; `pinnacle` covers pinnacle and its sister
  site. Every other book is its own engine.
- **The window is the whole game.** A post names one `team`, but the window carries
  both teams' player props for that game (a lineup change moves the team's batters
  and the opposing pitcher's strikeouts). Filter by `player`/`player_id` for the
  players you care about.
- **DFS pick'em products are included, with a null price.** PrizePicks, Underdog,
  Sleeper, DraftKings Pick6, Betr, SplashSports, OwnersBox, Dabble, and FanDuel Picks
  set a line without a two-sided price, so their `odds` is null. Their `line` and how
  it moves are still the signal, so the rows are kept.

## Loading

```python
import pandas as pd
df = pd.read_parquet("hf://datasets/SmartStake/mlb-lineup-reactions/mon=2026-05")
```

```sql
-- DuckDB, straight from the hub
SELECT book, count(*) FROM 'hf://datasets/SmartStake/mlb-lineup-reactions/**/*.parquet' GROUP BY 1;
```

## Reproduce a finding: which books reprice first

For total bases, the median time each book takes to make its first real price move
after a lineup post (lower is faster), straight from the hub with DuckDB:

```python
import duckdb
duckdb.sql("INSTALL httpfs; LOAD httpfs;")
print(duckdb.sql("""
WITH src AS (
  SELECT * FROM 'hf://datasets/SmartStake/mlb-lineup-reactions/**/*.parquet'
  WHERE market='bases' AND side='over' AND NOT is_suspended AND NOT is_alt),
seq AS (                                   -- consecutive quotes per selection per book
  SELECT event_id, engine, player, line, offset_sec, odds,
         lag(odds) OVER (PARTITION BY event_id, engine, player, line
                         ORDER BY offset_sec) AS prev
  FROM src),
firstmove AS (                             -- first >=1pt implied-prob move after the post
  SELECT event_id, engine, min(offset_sec) AS move_off
  FROM seq
  WHERE offset_sec >= 0 AND prev IS NOT NULL
    AND abs(1/odds - 1/prev) >= 0.01
  GROUP BY 1, 2)
SELECT engine AS book, count(*) AS reactions, round(median(move_off)) AS median_seconds
FROM firstmove GROUP BY 1 HAVING reactions > 300 ORDER BY median_seconds
""").df())
```

The full study centres each book against the field per event to strip coverage and
polling-cadence bias; this pooled version is a directional first look. Writeup:
https://smartstake.app/learn/mlb-lineup-drops

## Provenance, license, and responsible use

Odds were collected from public sportsbook and exchange feeds. Released under
CC BY 4.0 for research and educational use. This dataset is informational and
historical: past prices do not predict future outcomes, and betting carries risk of
loss. Not affiliated with any sportsbook. 21+.

## Citation

> SmartStake (2026). SmartStake MLB Lineup Reactions (2026). Hugging Face.