Here's our approach.
Every inch of the pitch has a non shot expected goal value associated with it based on the likelihood a side will eventually score from that field position.
So it's very low if you have possession near your own goal, much higher if you possess the ball inside the opposition box.
Successfully passing the ball from one point to another leads to a change in NS xG.
If you have the ball on the edge of your own box and roll a pass five yards forward to a defensive midfielder, you get credited for improving the side's NS xG, but not by much. Repeat the move on the edge of the opponent's box and you'll get a fair bit more.
Knock the ball backwards and your side "loses" NSxG, but at least you keep the ball.
Give away possession, either as a defender accidently passing to an opponent near your goal and you lose a combination of the NS xG you had and the NS xG your opponent gains.
Similarly, try and fail with a tricky pass inside the opponent's final third and you lose the fairly substantial NS xG your side had, along with the much smaller NS xG the opposition has gained.
This has led to three definitions for types of passes, two successful and one not.
Firstly, successful, creative passes that improve a team's NS xG.
Then, successful, backward passes that retain the ball, but "loses" NS xG
And finally unsuccessful passes that turnover possession.
These are further normalised for position played.
A defender will have a very different average profile in each category, compared to an attacking midfielder and the metric is also normalised to 100 passing attempts to put players who play for a possession poor team on a more level footing with Manchester City.
Here's an example.
From left to right. The average Premier League full back adds 0.64 non shot xG per 100 passing attempts by way of successful, creative passes. TA-A added 1.026 NS xG/100, an improvement of 0.386 on the average full back.
Backward, successful passes where NS xG was "lost", but possession was retained mirrored the average experience of a full back.
An average full back actually lost 0.8 NS xG / 100 via turnovers, TA-A did slightly worse, losing 0.894, but this is a function of the risk/reward balance. He is given free rein to get into advance positions, but the reward is well worth the extra risks taken.
Here's the differentials for every player who made at least 600 passing attempts for all 20 clubs last season.
They've been normalised for position, but many are a product of the role they are asked to play and the stylistic approach of the team they represent.
For instance, there's the different roles of goal keepers. Those who play out from the back, such as Alisson & Ederson added below average creativity, but are well above average when preventing turnovers.
Similarly, van Dijk is no more than an averagely creative passing centre back, but again the systematic demands of the team do not require him to be more adventurous. His main aim is to largely play unadventurous ball to slightly advanced players and again, not turn the ball over, which is reflected in his well above average turnover numbers.
Manchester City's adherence to keeping the ball is shown again by the turnover figures, with the perhaps significant exception of Sane, who is poor at retaining the ball, with little above creativity to compensate.
Passing volume ensures that their relatively unexceptional creativity, De Bruyne aside, invariably overwhelms an opponent.
And finally, the departing Hazard is a rare beast, who not only is above average creatively for his position, but also avoids the often boom or bust cycle by looking after the ball exceptionally well.
There are plenty of players who show above average creativity, but pay a relatively high price with turnovers.
