Where does Baseball Data Hub get its statistics?

From the Lahman Baseball Database (via the Chadwick Baseball Bureau) for career and season statistics, Retrosheet for game-by-game records, the Chadwick Bureau register for player identity, and the MLB Stats API for the season in progress.

How often is the data updated?

The current season is refreshed daily from the MLB Stats API; historical seasons are re-imported when Lahman and Retrosheet publish new releases, normally once a year. The data on this site was last refreshed on September 2, 2026.

Are Negro Leagues statistics included?

Yes. MLB recognized seven Negro Leagues (1920–1948) as major leagues in 2020. Those statistics appear on player pages and on dedicated Negro Leagues leaderboards, and an opt-in combined board follows the official record MLB adopted in 2024. The default all-time boards show the AL/NL record.

Is this season's data final?

No. Figures for the season currently being played are partial and complete only through the "Data updated" date printed on each page.

How are career totals calculated?

By summing the season rows shown on the same page. Rate statistics such as batting average, ERA and WHIP are then derived from those sums, so a career figure always agrees with the seasons above it.

Can I reuse this data?

The Lahman database is licensed under Creative Commons Attribution-ShareAlike 3.0 and Retrosheet data is provided free of charge under Retrosheet's terms, which require attribution. Both are credited in the footer of every page.

Data Sources & Methodology

Baseball Data Hub compiles 26,067 player records covering 1871 to 2026 from four sources: the Lahman Baseball Database distributed by the Chadwick Baseball Bureau, Retrosheet's game-by-game play accounts, the Chadwick Bureau identity register, and the MLB Stats API. Completed seasons come from Lahman (1871–2025); the season in progress is refreshed daily from the MLB Stats API. The underlying data was last refreshed on September 2, 2026, and that date is printed on every page. Career totals and rate statistics are computed from the season rows shown on the same page, so nothing on the site is carried in from a second, unstated source.

Data updated September 2, 2026

Where each number comes from

Data sources: what each one covers, how often it refreshes, and which pages it feeds
Source	What it covers	Refresh cadence	Pages it feeds
Lahman Baseball Database (via the Chadwick Baseball Bureau) Creative Commons Attribution-ShareAlike 3.0 Unported	Season-by-season and career batting, pitching and fielding lines; team seasons; awards; Hall of Fame voting; salaries; college and biographical registers, 1871 to the most recent completed season.	Re-imported when the Chadwick Bureau publishes a new release, normally once a year after the World Series.	Player pages, team-season pages, franchise pages, leaderboards, award pages, season pages.
Retrosheet Free of charge and copyrighted by Retrosheet; redistributed under their terms.	Game-by-game play accounts: box scores, game logs, starting lineups, ballpark usage and daily splits.	Re-imported when Retrosheet publishes a new season file, normally once a year.	Game pages, player game logs, ballpark pages, day-in-history pages.
Chadwick Bureau Register Creative Commons Attribution-ShareAlike 4.0	The cross-source identity table that ties a Lahman playerID to a Retrosheet ID, an MLBAM ID and a Baseball-Reference ID, so one person is one page.	Re-imported alongside the Lahman database.	Every player page; the identity redirects that keep old URLs alive.
MLB Stats API Public MLB endpoint, used for current-season figures only.	The in-progress season: active rosters, daily batting and pitching totals, standings, injuries and debuts.	Fetched daily; the date the figures were last pulled is printed on every page as "Data updated".	Active-player pages, the current-season page, the homepage counters, current-season leaderboards.
Negro Leagues Database (Seamheads) as distributed through Lahman Used under the terms of the Lahman Negro Leagues distribution.	Documented Negro Leagues game records, 1920–1948, which MLB recognized as major league in 2020.	Re-imported alongside the Lahman database.	Negro Leagues sections on player pages, the Negro Leagues leaderboards, and the opt-in combined leaderboards.

How current is this?

The underlying data was last refreshed on September 2, 2026. That date appears in the footer of every page and in each page's dateModified structured data, and it tracks the newest data file on disk rather than the time the site was last rebuilt — so a rebuild that changes no numbers does not claim the numbers changed.

Statistics run through the 2026 season. Completed seasons come from the Lahman release (1871–2025); the season currently being played is layered on daily from the MLB Stats API and is partial by definition.

How derived statistics are computed

Batting average, on-base and slugging: Computed from the summed counting stats on the page (H ÷ AB; (H + BB + HBP) ÷ (AB + BB + HBP + SF); total bases ÷ AB), so a career rate always agrees with the season rows above it.
ERA and WHIP: Computed from earned runs, hits, walks and recorded outs: (ER × 9) ÷ (IPouts ÷ 3) and (BB + H) ÷ (IPouts ÷ 3).
Career totals: Summed from the season rows shown on the same page, including any Negro Leagues seasons where the player has them; nothing is carried in from a second source.
PIV and Pitcher PIV: Baseball Data Hub's own metrics, computed per season against that season's league average and then summed. The full formula is published at /about/piv-methodology.
Leaderboard qualification: Career batting-rate boards require 3,000 at bats and single-season boards require the era-appropriate plate-appearance minimum; the exact threshold in force is printed on each board.

Every abbreviation used anywhere on the site is defined at the statistics glossary.

Known gaps and caveats

These are the places where the data is incomplete or contested. They are listed here rather than buried, because a number is only as useful as the reader's ability to judge it.

The in-progress season is partial: Figures for the season currently being played are refreshed daily and are complete only through the "Data updated" date printed on the page. They are not final and will change.
Negro Leagues records are incomplete by nature: The surviving record covers documented league games only. Box scores for many contests were never printed or have not been recovered, so Negro Leagues career totals are a floor, not a full accounting. Default leaderboards therefore rank AL/NL records; separate Negro Leagues boards and an opt-in combined board are provided rather than silently merging the two.
Game-level coverage starts in 1898: Retrosheet play accounts thin out sharply before the twentieth century, so game logs, box scores and splits are unavailable for the earliest seasons even where season totals exist.
Nineteenth-century statistics carry source disagreements: Records from 1871–1900 were reconstructed from newspaper accounts, and different compilers reach different totals for some players. Figures here follow the Lahman/Chadwick reconciliation.
Some statistics were not recorded in every era: RBI (before 1920), sacrifice flies, caught stealing, intentional walks and hit-by-pitch were not tracked league-wide for parts of baseball history. Blank cells mean "not recorded", not zero.
WAR is not computed here: Where WAR is discussed it is explained as a concept; Baseball Data Hub does not publish its own WAR figures. PIV is the site's own metric and its formula is published in full.

How the Negro Leagues are handled

MLB recognized seven Negro Leagues (1920–1948) as major leagues in 2020. Baseball Data Hub publishes those statistics on player pages and gives them their own Negro Leagues leaderboards.

The default all-time leaderboards rank American and National League records (plus the AA, FL, PL and UA) under the traditional qualification rules. A separate, opt-in combined view follows the official record MLB adopted in 2024, with the career and single-season minimums prorated for the shorter Negro Leagues schedule. The two views are linked from each other and each says which record it is showing. Nothing is silently merged.

Corrections

If a figure here disagrees with the source it is drawn from, that is a bug worth fixing. Every page states which dataset a number came from, so a correction can be traced back to the release that carries it.

Data & Methodology: Frequently Asked Questions

Where does Baseball Data Hub get its statistics?: From the Lahman Baseball Database (via the Chadwick Baseball Bureau) for career and season statistics, Retrosheet for game-by-game records, the Chadwick Bureau register for player identity, and the MLB Stats API for the season in progress.
How often is the data updated?: The current season is refreshed daily from the MLB Stats API; historical seasons are re-imported when Lahman and Retrosheet publish new releases, normally once a year. The data on this site was last refreshed on September 2, 2026.
Are Negro Leagues statistics included?: Yes. MLB recognized seven Negro Leagues (1920–1948) as major leagues in 2020. Those statistics appear on player pages and on dedicated Negro Leagues leaderboards, and an opt-in combined board follows the official record MLB adopted in 2024. The default all-time boards show the AL/NL record.
Is this season's data final?: No. Figures for the season currently being played are partial and complete only through the "Data updated" date printed on each page.
How are career totals calculated?: By summing the season rows shown on the same page. Rate statistics such as batting average, ERA and WHIP are then derived from those sums, so a career figure always agrees with the seasons above it.
Can I reuse this data?: The Lahman database is licensed under Creative Commons Attribution-ShareAlike 3.0 and Retrosheet data is provided free of charge under Retrosheet's terms, which require attribution. Both are credited in the footer of every page.