DATA TRANSPARENCY
Data Sources & Credits
Where Perfect 20's historical football data comes from, how it is transformed, and which parts are produced by the project.
How to read this notice
Perfect 20 combines factual football data published by third parties with fields produced by the project's import, rating, review, and simulation pipelines. The source licenses below apply only to the upstream material they cover. They do not license unrelated Perfect 20 code, design, text, or service. Perfect 20 also does not change or narrow rights granted directly by an upstream license.
nflverse
Perfect 20 uses files published by the nflverse-data project for player and roster identity, seasons and positions, draft information, 1999–2025 player statistics, and 1999–2025 schedules and game results.
The upstream project identifies Tan Ho and Sebastian Carl as authors and publishes the repository under the Creative Commons Attribution 4.0 International license (CC BY 4.0). Read the official CC BY 4.0 terms.
Perfect 20 filters, selects, normalizes, joins, and transforms those source files and calculates additional fields from them; changes were made. The source material is provided under the upstream license and its warranty disclaimer. nflverse, its authors, and its contributors do not sponsor, endorse, or operate Perfect 20.
FiveThirtyEight NFL Elo game data
Perfect 20 uses FiveThirtyEight's historical NFL game file for pre-1999 game dates, teams, scores, postseason status, and neutral-site status. It maps team identifiers and derives its own franchise records and related fields from those results. Perfect 20 does not use FiveThirtyEight's Elo forecast values as player ratings.
Copyright (c) 2021 ABC News Internet Ventures. The nfl-elo-game repository is published under the MIT License. Perfect 20 filters and transforms the source rows; changes were made. FiveThirtyEight and ABC News Internet Ventures do not sponsor, endorse, or operate Perfect 20.
MIT License notice
Copyright (c) 2021 ABC News Internet Ventures
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Fields produced by Perfect 20
Perfect 20 assigns internal identifiers and produces normalized mappings, availability values, era-relative percentiles, ratings, trait values, confidence values, rationales, tags, QA/review artifacts, and simulation results through project code, curated inputs, and offline model-assisted processing.
These are not ratings supplied or endorsed by nflverse or FiveThirtyEight. Some fields are calculated from upstream factual inputs, so the attribution above still applies to those inputs. “Produced by Perfect 20” describes the processing path; it does not claim ownership of upstream facts or override third-party license rights.
Read the rating methodology for the public model overview and the Terms of Use for service-access rules.
Corrections
Send source or attribution corrections to [email protected].