Where the answers come from

Rosters: three sources combined

A player counts for a team if any of these lists him:

• Wikidata (CC0), the knowledge base behind Wikipedia: every “member of sports team” statement, including earlier clubs (not just the current one).
• English Wikipedia's team player categories, such as “Dallas Cowboys players” or “Sweden international footballers”.
• For the NFL, each team's current roster and practice squad as published on ESPN, which also fills in positions for current players.
• English Wikipedia player articles (the career in each player's infobox), used to check player reports.

For NFL questions we use American football players; for soccer, association football players. Clearly broken entries are filtered out.

• NFL: all 32 franchises, including earlier homes and names (Oakland and Los Angeles Raiders, St. Louis and Cleveland Rams, San Diego Chargers, Baltimore Colts, Houston Oilers, Chicago Cardinals).
• Positions come from Wikidata's “position played on team” field. Halfbacks and fullbacks count as running backs.
• Soccer: 53 clubs across England, Spain, Italy, Germany, France, Portugal, the Netherlands, Scotland, MLS, Brazil, Argentina, Turkey and Saudi Arabia, plus 35 men's national teams.
• “Played for both” questions are the overlap of two rosters, kept only when the overlap has between 12 and 220 players.

How rare: Wikipedia pageviews, then real answers

Each answer's projected share comes from a model of how likely players are to name him, fitted on the answers players have actually given and refitted as more come in. It uses his English Wikipedia pageviews (from Wikimedia's public pageview data), how many Wikipedia language editions cover him, how many years he was with the team (Wikidata), how often readers click from the team's Wikipedia article to his (Wikimedia's public clickstream data), and whether he played there in the last five seasons. A question's own answers take over gradually: share = (times named + 300 × projected share) ÷ (answers + 300). A guard keeps club legends from scoring like unknowns: the best-known 5% of a question's answers (at most 20) never score above Known, the best-known 12% never above Sharp. Points then come from where the answer sits when every right answer is lined up from most to least named — aiming for about 25% of answers Obvious (Chalk in the NFL), 25% Known, 20% Sharp, 18% Rare and 12% Deep Cut; the cut points along the line are adjusted each day from what the last week's answers actually scored (see points). Each day's line-up is built once from the answers given up to the day before and doesn't move during the day, so a name scores the same for everyone that day; replays of a past day use that day's line-up.

Player reports

When two players report the same missing answer (or several players type the same name), we check it against that player's English Wikipedia article: the clubs (loans included) and national team in his infobox, or the NFL teams and position, and the team's player categories. If the article shows he fits the question, he's added and counts for everyone, usually within minutes; if it doesn't, nothing changes. Reports the article can't settle go to a person. For a few reports an AI model helps read the article, and its answer only counts when it quotes the article word for word. How many people send the same report decides when we check it, never whether he counts.

Known gaps

• Players signed in the last few weeks, and some rookies, may be missing until Wikidata catches up.
• Position questions rely on the position recorded in Wikidata, which is incomplete for some older players.
• Practice-squad and preseason-only players are included only when Wikidata lists them.
• A few entries are wrong in Wikidata itself. Reports are checked automatically against the player's English Wikipedia article (the clubs and national team in his infobox, loans included), and an answer is added only when that source shows it; reports it can't settle go to a person.

If a right answer didn't count, report it. Once two players report the same name, we check it automatically; confirmed answers count for everyone, usually within minutes. Scores already played don't change.