As we often discuss, Expected Goals analysis of a match has to go hand-in-hand with actually watching the chances themselves, and nowhere is this more obvious than in Man United's 2-0 win over Man City in the derby on Sunday.
The xG scores suggest a comprehensive win for United (1.75 v 0.6), and in the main they deserved to win, City turning in one of their most toothless performances of the season so far.
But the xG should have been much closer than some models suggested. In the second half Ederson's poor touch on the line ran across his body and he was able to clear it just before Anthony Martial reached him. However, because Martial got a slight touch on the ball, it is registered as a chance, and one with a gigantic xG of 0.93 with one well-used model.
It's farcical to suggest this was a clear chance - and similarly, Raheem Sterling's stretch to reach a cross with 15 minutes remaining - barely getting a toe to the ball - received a much higher xG (0.4-0.5) than it should have based on the nature of the chance.
In fact, the xG for both teams in this match should have been extremely low. There wasn't a clear opening in the game and this is a key example of xG on its own not telling the full story.
Dortmund remain very much in the title hunt with Bayern after a hard-fought 2-1 win away at Gladbach, but it was very much a case of good finishing which won the day.
Lars Stindl (0.45 xG) and Breel Embolo (0.63 xG) missed great chances, the latter skewing wide when completely free in the area. While at the other end Thorgan Hazard, featuring against his former club, curled home a beauty (0.15 xG) and Achraf Hakimi (0.3 xG) stabbed home to seal the win.
Dortmund, as they have done on more than one occasion this season, are confounding xG with their performances - but can they keep it up until the finish line?
What is xG check?
Each week FC will aggregate the Expected Goals (xG) ratings from three respected sources and provide an average for both the home and away team. From there we will assess which matches have ended in a different manner than the xG would suggest.
EXPECTED GOALS (xG) assesses the quality of a shot based on several variables such as assist type, shot angle and distance from goal, whether it was a headed shot and whether it was defined as a big chance. From there that shot is assigned an xG score and the cumulative total of these scores provides a team's xG for a match.Stats Definition
But sometimes, xG doesn't tell the whole picture, so we also analyse the highlights of these games to look at the chances created by teams in a little more detail.