Errata on FBref.com
How we determine player positions
We have two categories of positions, primary and secondary. Primary positions are the four basic groups of positions, while secondary positions are more specific to their role and location on the pitch. These positions can be viewed at the top of a player's page. A player may have multiple positions assigned to them depending on which positions they have played over the course of their career.
- Primary Positions:
- GK - Goalkeepers
- DF - Defenders
- MF - Midfielders
- FW - Forwards
- Secondary Positions:
- CB - Center Backs
- FB - Fullbacks
- DM - Defensive Midfielders
- CM - Central Midfielders
- WM - Wide Midfielders
- AM - Attacking Midfielders
We use formation data from each match to determine positions. In order to assign a primary position to a player, we require that they appear in the equivalent of 20 full matches or make 20 starts at a position (depending on the available formation data). However, for goalkeepers, we only require 5 matches. For secondary positions, we require at least 40 matches played since these are more distinct positions.
Positions By Season
In addition to assigning overall positions to a player, we also assign them positions for each season/competition. This is done to show only the positions a player has played during that season and not the positions they may have played earlier or later in their careers. There is no minimum playing time to qualify for a position on the season-level.
Positions By Match
Similarly, we assign players positions for each match in which they appear to indicate which position they played in a given match. Because of this, a player's match, season and career positions may differ.
We do our best to assign the correct position values to each player based on the data available. Please note that we do not have complete formation data for all of our seasons and competitions. If you believe there is an egregious error in our positional data, please let us know through our contact form.
How we determine player nationalities
1. Identify all pieces of evidence that may confer national affiliation to a player. This naturally includes appearances for senior or youth national teams, but also includes secondary pieces of evidence such as country of birth, family relationships, and stated preferences.
2. If a player has represented the senior team for a FIFA member association in an official competition, this will usually be their permanent and immutable primary nationality. If a player has represented a youth team (or the senior team in an unofficial competition) for a FIFA member association, this will be their permanent primary nationality unless and until they are granted approval by FIFA to change nationality. If a player has never represented a FIFA member association on any level, we are typically making an unscientific guess as to the player's nationality based on the other factors (country of birth, family, stated preferences).
3. Any other national affiliations we might identify that are different from the player's primary nationality is displayed as a secondary nationality. For players who have not represented the senior team for a FIFA member association in an official competition (or been approved for a one-time nationality change), any secondary nationalities a player might have may plausibly become the player's primary nationality in the future. Otherwise, secondary nationalities have no special meaning.