Data and sources

The spreadsheet the league has kept since 2014 is the only source for the years before the record reaches game level: standings, podiums, the lifetime ULTIMATES and the noteworthy events. It is imported once and never written to. Where it disagrees with the record, the record wins and the difference is ledgered on Data notes.

From 2021 on, Sleeper's API supplies the league at game level: every weekly matchup and both lineups, per-player scoring, the draft boards, the whole transaction log and the playoff brackets. It is also what the Live page reads, in the browser, on every visit.

2017 to 2020 were played on Yahoo, whose API no longer grants access to a league this old. The seasons were recovered page by page from the league's own Yahoo pages: team scores, box scores with both lineups, the draft boards for 2017, 2018, 2019, 2020, and the transaction log. The recovered pages are committed with the site, so a build needs no network.

The scoring for those years was never labelled anywhere. It was recovered by testing settings against the box scores until they reproduced, and the result is in the league's config: see the ground rules on Data notes.

Player identity, bios, headshot ids, injury listings, snap counts and play-by-play scoring come from nflverse's public data releases, snapshotted into the repo for every player the league has ever rostered. 758 of 758 players are joined to their Sleeper ids, with none unmatched; the join is itemised on Data notes.

The weekly tiers on the site are Boris Chen's, published at www.borischen.co. They are built by Gaussian mixture model clustering of expert consensus over FantasyPros expert consensus rankings, published at www.fantasypros.com. Tiers only, as published; no rankings or projections are reproduced.

All of it is merged into one model at build time and every page renders from that model alone. The merge runs 877 checks against the sheet and against Sleeper's own records, and refuses to be quiet about a new disagreement. 9 seasons carry game-level data. The receipts, the ledgered differences and the refresh schedule are on Data notes.