Data & Algorithms
An explanation of how we manage data and build our algorithms.
Expected Transfer Value (xTV)
The Expected Transfer Value model is a Machine Learning model that estimates the expected transfer fee value for a given player. It uses information on the player’s Skill, Potential, recent performance, contract duration, position and others to estimate an accurate transfer fee.
The FootballTransfers Skill is designed to provide an indication of a player’s Skill level. It does so by measuring the influence of a player on his team. The Skill score is computed on a per ]pmatch basis. It is able to calculate the influence that the player has on the team he plays for.
The input variables of the Skill data point are:
- Number of minutes a player played in a particular position
- Type of match (e.g. league, cup, international)
- Strength of the league and the opponent
- The number of goals scored and conceded by the player’s team.
The algorithm determines the skill level of a player based on historical information. A player’s skill is based on his performance in matches, where more recent matches are more relevant and have a higher weight than older matches.
The Potential estimates a football player’s peak ability, which most players reach in their late twenties. Players in more defensive positions like goalkeepers and defenders typically reach their peak abilities at a later age than players in more offensive positions like midfielders and attackers.
We define a football player’s peak ability as the maximum Skill level a player is expected to reach throughout his career based on their Skill development to date. Potential is computed by projecting a player’s Skill development to a date in the future based on the Skill developments of older players who had a similar Skill development as the player.
© SciSports. Read more about the methodology behind the Skill and Potential metric here.
Player Roles (Positions)
At the Playing Style of a player, the playing style of players is indicated via scores on a range of different Player Roles. In total, FootballTransfers identified 22 Player Roles. Player Roles help contextualise an individuals role and tendencies on the pitch. Below an overview of the definition of each of the 22 roles.
Line Keepers are regularly involved with making saves close to their goal-line and tend to be less involved in possession actions. This type of goalkeeper is less inclined to perform defensive actions or involvement in build-up play away from their goal. Any significant involvement in possession build-up is rare for Line Keepers.
Sweeper Keepers look to perform defensive actions away from their goal-line and claim crosses on a regular basis. This type of goalkeeper will also be proactive in recovering possession for their team and produce a moderate level of actions in build-up play which is primarily directed to wider areas. High involvement on their own goal-line is rare for Sweeper Keepers.
Ball Playing Keeper
Ball Playing Keepers frequently register actions in central areas to kickstart build-up. This is also paired by a high number of actions in possession, mostly in central areas, compared to other goalkeeper types. This goalkeeper is not regularly involved in defensive actions such as interceptions or recoveries in their own third.
Defensive Backs are not regularly involved in attacking actions such as crossing, dribbling or build-up play. Instead, they perform a high number of recoveries per match as well as pressures, tackles, fouls and duels. Advancing into the final third on the overlap is less likely for this type of player.
Wing-backs are highly involved in offensive actions mostly comprising of crosses, dribbles and chance creation in wide areas. A high number of overlapping runs are also common for this type of full-back who is most often offensively orientated. Defensive actions such as pressures, tackles, fouls and duels are less common for wing-backs although still at a moderate level in some cases.
Inverted Wing Back
Inverted Wing Backs are primarily involved in creating chances from wide areas as well as frequent involvement in build-up play. Unlike other full-backs, the Inverted Wing Back registers a high number of underlapping runs and receptions in the halfspace. This type of player does not engage in pressures, tackles, fouls and duels on a regular basis.
Stoppers are regularly involved in defensive headers as well as intercepting passes by the opposition. This type of player does not register a high amount of actions in possession either through dribbling or passing and tends not to tackle on a regular basis.
Ball Playing Defender
Ball Playing Defenders tend to play a high number of short-range passes to teammates as well as low-tempo actions in build-up play. Those characteristics are often complimented by a moderate level of engagement in tackles. Fulfilling this criteria is frequently achieved by defenders performing a moderate amount of actions in a high defensive line and fewer interceptions than other types of defender.
Ball Winning Defender
Ball Winning Defenders perform a high number of recoveries in their own third as well as being frequently involved in a high defensive line. These defenders do not find themselves regularly performing short passes and headers in a defensive manner. In sum, players categorised in this role regularly regains possession but is not highly involved with the ball at their feet.
Ball Winning Midfielder
Ball Winning Midfielders are inclined to perform a high number of defensive actions such as pressures, tackles, fouls and duels. These players tend to be more involved out of possession with low ranking numbers, on average, in areas such as passes to the final third and creating chances.
Holding Midfielders tend to play in a conservative manner with very few chances created in the final third. This type of player also tends to play in a deeper position than other midfielders, therefore not receiving the ball in the final third on a regular basis. Players in this role often press the opposition instead of taking on creative responsibilities in possession but tends not to get involved in a high amount of physical duels like tackling and fouls.
Deep Lying Playmaker
Deep Lying Playmakers frequently play passes in their own final third as well as into the opposition’s final third. These actions on the ball result in many actions in possession build-up and less involvement from a defensive standpoint. Physical actions and ball-carrying is less regular for this type of player.
Box-to-Box Midfielders are primarily involved in a high number of pressing actions in the opposition’s half. When in possession, this type of midfielder does not dribble with the ball on a regular basis and but creates chances through passing on a moderate basis. From a defensive perspective, this midfielder is moderately involved in recoveries and pressing in high areas, though they tend not to do so in close relation to their teammates.
Advanced Playmakers register a high number of passes into the final third in matches they play as well as directly creating chances in possession. Players within this role tend not to perform a high number of defensive actions including recoveries in their own final third in favour of a more creative role on the ball.
Wide Playmakers are regularly involved in possession with frequent reception of possession in the halfspace. A moderate level of chance creation can come from wide areas with a high number of chances also created in central areas. This type of attacker does not perform a high amount of crosses or dribbles into the middle of the pitch although they can produce a moderate amount of chance creation from central areas.
Classic Wingers regularly create chances in possession from wide areas rather than in the middle of the pitch. They are also inclined to perform a high number of crosses that are near to the opposition’s byline. Players within this category are mostly involved in wide areas and do not shoot from outside the penalty area on a regular basis.
Inside Forwards are players that frequently receive possession in the halfspace between the opposition’s defenders. When in possession of the ball, these players look to create chances from wide areas with direct involvement in chance creation, build-up play and cutting inside through dribbles. Players within this role are often involved around the penalty area instead and also register less crosses than other forwards. These forwards are less rigid in their defensive structure with limited involvement in keeping a compact unit out of possession.
Shadow Strikers are primarily involved in making short passes to teammates and often into the final third. They also register at least a moderate level of shots from outside the box on average but are not regularly involved inside the penalty area. Pressing the opposition high up the pitch is rare for this type of player in favour of more offensive contributions in possession.
A Target Man produces a high number of pressures, tackles, fouls and duels per match as well as pressing the opposition high up the pitch. This type of striker does not register high shot output although any shots tend to come from receiving crosses or headers. Overall involvement within the penalty area is lower for a Target Man compared to other strikers.
Poachers are primarily involved in offensive actions within the penalty area, often receiving the ball and shooting within the penalty area. They also look to shoot when receiving crosses from teammates. This type of striker does not regularly create chances or become involved in defensive actions such as pressures, tackles, fouls or duels, instead more involved in shooting within the penalty area.
Mobile Strikers tend to register a high amount of offensive actions including receiving the ball, dribbling in the final third and shooting from inside the box. This type of striker also receives possession in the halfspace on a regular basis. They tend to not be involved in defensive actions such as pressures, tackles, fouls or duels.
Pressing Forwards are inclined to put defensive pressure on the opposition in the final third and also register a moderate number of tackles, fouls and duels on average. Offensive responsibilities for this type of forward is often limited to a low level of shot output in the box and possession involvement in the opposition’s final third. Players within this role type do not perform a high number of headers in attacking areas but do register a moderate number of receptions in the halfspace.