Ebb-and-flow: Using xPG to capture soccer’s momentum swings

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Ebb-and-flow: Using xPG to capture soccer’s momentum swings

Recently we introduced Expected Possession Goals (xPG) as an experimental metric. In our latest article, we introduced four uses of xPG. Like any good experiment, things are subject to change as you take input. To help xPG be a little easier to consume, we’re updating some of the terms to be more understandable:

Chance xPG (formerly called Positive xPG) is the total value of a possession based on weighted values gained from actions such as ball-winning actions, passes, dribbles and shots. It is assigned to all the players involved in a possession. A player or team with high Chance xPG is getting the ball into higher opportunity areas for a shot. Chance xPG is expressed in a positive value.

Shot xPG (formerly called Successful xPG) is the total Chance xPG earned by possessions ending in a shot. Players and teams with a high Shot xPG relative to Chance xPG are ones which are good at turning chances into shots. Easy, right?

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The Next Level of xG: Expected Possession Goals

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The Next Level of xG: Expected Possession Goals

Using xPG variants to assess risk-and-reward of the game

We introduced Expected Possession Goals (xPG) in two recent articles. xPG groups and rates the outcome of a possession and began from an idea that every action in the possession connects to create a shot. Here, we’re introducing new xPG variants, extensions to the original xPG definition to assess the risks and rewards inherent in a soccer possession.

xPG rates a group of uninterrupted events - or when an interruption lasts fewer than two seconds - based on where the ball travels. It assumes the purpose of the possession is to move the ball within shooting distance.

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