What is xG, xGA and other similar terms?
You probably heard of expressions like xG, xGA, NPxG or xG90 and maybe you did not understand what they meant?
In this article, we will explain everything about Expected goals so you can shine next time somebody wonders what xG is. This is an english version of our xG guide in Swedish.
So if we want a really simple answer xG is short for expected goals and is just as it sounds a measurement of how many goals are expected from the play.
This can both be part of an individual player to see how high xG they have during a season or on a team to see how high xG they had in a single match.
How to calculate xG?
xG or expected goals are a pretty advanced calculation. But to simplify it we can say that you calculate how high chance a certain type of finish has from a certain position on the field.
A shot a few yards out have a much higher chance of resulting in a goal than a header from outside the penalty box.
That way one shot may give an xG of 0,02 and another of 0,2 for example. Then you add them all up to see for example that Liverpool maybe had an xG of 2,4 in a game.
If they scored just once in that game you can see that they created chances to score more. But if they won that game by 4 goals you know that they got more goals than they deserved.
Other terms to know:
xG = Expected goals. How many goals a player or team is expected to score.
xGA = Expected goals against. How many goals a team is expected to concede.
NPxG = non-penalty xG. Here you see how high xG a player or team has if you exclude penalties. Especially good when comparing players as penalties can distort the xG data pretty much if you compare a penalty taker in one team with a non-penalty taker in another team.
xG90 = Here you see how high the xG is per 90 minutes of play. A good way to even out if you for example compare players and one player ofter get subbed off after 70 minutes or missed a few weeks with injuries.
What can you use xG for?
Here on Dagensbetting.se we use xG and xGA a lot when we calculate the probability of different games to see where bookmakers have gone wrong with their odds.
But for the normal fans out there it’s a very good way to get a fair view of a player or team to see how they really performed and a good way to remove some of the natural variations that is a big part of football.
It’s also worth nothing that the best strikers in the world normally outperform their xG as they are not average when it comes to finishing. This way you can also see what makes a striker good.
If they outperform their xG a lot they are probably one of the world’s best finishers. But if they score a lot of goals but their xG matches their goals perfect then their strength is more in finding the right spot, being in the right place and time that run perfectly.
So they create more chances but maybe not put them away as often.