Overview
Leviathan Isolated Impact:
- Offense:
- Positive - player increases their team’s offensive chance creation (good).
- Negative - player decreases their team’s offensive chance creation (bad).
- Defense:
- Positive - player increases the opposition team’s offensive chance creation (bad).
- Negative - player decreases the opposition team’s offensive chance creation (good).
Shooting Impact:
- Outfield Player:
- Positive - player’s shooting ability increases probability that a shot results in a goal (good).
- Negative - player’s shooting ability decreases probability that a shot results in a goal (bad).
- Goalkeeper:
- Positive - goalkeeper’s shot stopping ability increases probability that a shot results in a goal (bad).
- Negative - goalkeeper’s shot stopping ability decreases probability that a shot results in a goal (good).
Offense
Football players primarily impact the number of goals scored by their team by contributing to their team’s generation of quality scoring chances. The top third of the player iso-impact card illustrates this impact. Red areas show where the individual player causes their team to generate more quality scoring chances, relative to league average. Blue areas show where the individual player causes their team to generate fewer quality scoring chances, relative to league average. In the given example player card, which estimates Alexis Sanchez’s ability after the conclusion of the 2014-15 EPL season, Alexis Sanchez caused his team to generate a greater than average quantity of quality scoring chances throughout much of the penalty box, particularly in the left half of the box, and a smaller than average quantity of quality scoring chances in a few spots, such as the top of the box on the right side and directly in front of goal on the right side. In total, Alexis Sanchez caused his team to generate 0.05 more expected goals per 90 minutes, which means that Sanchez increases his team’s expected goals per 90 minutes by 4.3% relative to the average xG/90 of EPL teams during the 2014/15 EPL season.
Shooting
For outfield players, this is the shooting ability of the player after taking into account the type of shot, the location of shot, and the goalkeeper they are facing. In the example, Sanchez’s shooting ability is far better than the average outfield player; relative to the league average shooter, a shot taken by Sanchez is 17.7% more likely to result in a goal.
For goalkeepers, this is the shot stopping ability of the keeper after taking into account the type of shot, the location of shot, and the shooter they are facing. The output for each individual keeper is the probability that a shot against the particular keeper will result in a goal, relative to league average.
Defense
Football players impact the number of goals scored by the opposition team by contributing to their team’s defensive efforts to suppress the opposition team’s generation of quality scoring chances. The bottom third of the player iso-impact card illustrates this impact. Red areas show where the individual player causes the opposition team to generate more quality scoring chances, relative to league average. Blue areas show where the individual player causes the opposition team to generate fewer quality scoring chances, relative to league average. According to the Alexis Sanchez example card, Sanchez caused opposition teams to generate a smaller number of quality chances from directly in front of goal and on the high left and right sides of the penalty box. Sanchez’s presence, though, caused the opposition to generate more quality chances to the left and right sides of the penalty box down towards the goal line. In total, Sanchez caused opposition teams to generate 0.04 less expected goals per 90 minutes, which corresponds to 3.1% less than league average.