I will update the Player Value for the upcoming season bi-weekly or monthly.
Dave Laidig has applied his player rating system to Serie A’s players in 2018/19 season. This metric assigns each player’s contribution to the team’s result. The fundamental calculation is the difference between the chance of scoring when a player gets the ball and the chance of scoring when the player completes an action.
A zonal non-shot Expected Goal (xG) model was generated. It is our chance of scoring; in brief, shots, dribbles, passes, and defensive actions into chronological order. Possession groups are defined: a possession starts with a shot, a dribble, a completed pass, or an incomplete free-kick, corner, throw-in. A possession ends with a shot, an opponent offensive action (pass/dribble/shot), or end of half/game. The pitch is divided into over 100 zones, and the average expected possession result (in xG) for each zone is calculated. For every possession, each zone is only counted once. The free-kick, the corner kick, and the penalty are separated from the regular run of play touches. In the end, a zonal non-shot xG value is calculated based on all the possessions. It is our chance of scoring and how every action fo the player is rated. For more detail, please click here.The value of each player on their team’s winning is rated in eight categories:
- Shot value
- Pass value
- Turnover or Loss-of-possession value (TO/LOP value)
- Movement Value (Move value)
- Defensive (Turnover) value (DEF TO value)
- Defensive (Pressure) value (DEF Pressure)
- Fucked-up value (conceding PKs and red cards) (FUP)
- Goalkeeper value (GK value)
Shot value
Shot value is calculated as follow:
For a shot on target:
Shot value = post-shot xG – zonal non-shot xG of where the shot is made
For a shot off target:
Shot value = standard xG – zonal non-shot xG of where the shot is made
The zonal non-shot xG is subtracted to avoid duplication because that value is counted in other categories.
Pass value
Pass value = The zonal non-shot xG of where the pass is received –
The zonal non-shot xG of where the pass is made
Only the successful pass is counted. The unsuccessful pass is counted in TO/LOP value.
Turnover or Loss-of-possession value (TO/LOP value)
TO/LOP value summates the (negative) value of non-shot actions that end the possession for a team. Losing the possession means a team has zero percent chance of scoring, therefore:
TOP/LOP value = 0 – zonal non-shot xG of where the turnover is made
The values represent the expected possession results that were lost by the player.
Movement value (Move value)
Move value = zonal non-shot xG of where a carry ends – zonal non-shot xG of where a carry starts
DEF TO value or DEF Pressure value
When a defensive action forces a change of possession:
DEF TO value = Opponent zonal non-shot xG of where the possession ends + zonal non-shot xG of where the turnover is forced
When a defensive action doesn’t force a change of possession:
DEF Pressure value = zonal non-shot xG of where the defensive action is made
Fucked-up value (conceding PKs and red cards) (FUP)
The FUP Value represents game-changing mistakes such as red cards and conceding a penalty kick.
For a red card:
FUP Value = 1.45 * (Minutes Excluded from Game/Game minutes)^0.85.
For fouls leading to a penalty kick:
FUP Value = -0.55 xG equivalents for the player who commits the foul
And:
FUP Value = +0.2 xG equivalents for the player who suffers from the foul
GK value
GK value = Post shot xG – shot’s result (1 for goal & 0 for non-goal)
CREATE index = Pass value + TO/LOP value + Move value
DEF index = DEF TO value + DEF Pressure value