What is an attacking player in soccer supposed to do?
We'll start here: score goals. And well, that's mostly it: Score a lot of goals, and no one really cares about anything else. Can't dribble? Won't defend? Don't like to pass? If you can overcome all that and find a way to get the ball past the opposing goalkeeper on a consistent basis, then we'll forgive all of your other sins.
For all of the mysteries and complexities of the beautiful game, the ability to smash the ball over the goal line, again and again, vastly outweighs anything else a player might be able to do on a soccer field.
But if we go one step back, then someone still has to create the opportunity for the goal, right? How do you do that? Most of the time, by passing the ball to a teammate who is in a better position to score. If goal-scoring is the most important thing -- the conversion of chances into goals -- then it stands to reason that the ability to create the capacity for a goal to be scored is the second-most-important thing.
Of course, the ball doesn't just magically appear in the area where it can then be turned into a chance, either. Someone has to create the capacity for goal scoring, and someone also has to create the capacity ... for the capacity of goal scoring to be created. Put more simply: Someone has to move the ball up the field.
On offense or in attack, however you want to phrase it, there are three phases: moving the ball up the field, creating chances and taking shots. We can measure all of these things in different ways, but what if we tried to combine the various metrics accounting for all three phases into what everyone loves: a single number stat? And what if we then used those to do the other thing that everyone loves: rank the best players in the world?
The methodology
We're operating from the following premise: simpler is better.
I'm not trying to create any kind of predictive metric. I don't want to account for team or league dynamics. I don't care about age curves. I'm ignoring defense and off-ball movement. I just want to know what players are moving the ball up the field, creating chances and scoring goals. And then I want to know who is doing it most often.
In baseball and basketball, they have something called "game score" -- an adjusted point total that awards pitchers and all basketball players for all of the basic stats they accrue in a single game. How much is eight rebounds, 15 points and two steals worth compared to 35 points and nothing else? Game scores can help. That doesn't exist in soccer, so we're devising a way to do something similar.