Chelsea have experienced a frustrating few weeks.
The Blues lost 1-0 after 90 minutes of domination against Newcastle United, before drawing 2-2 with 10-man Arsenal at Stamford Bridge three days later.
Frank Lampard has since publicly referenced Expected Goals (xG) in response to his team’s failings, by suggesting that his side should have 10 points more than their current tally of 40.
“I know that the Expected Goals – I don’t like too many stats on Expected Goals – but we are bottom of the league at home in taking them [shots] and we are second to Liverpool in creating them. So that is just two ends of the scale that shows where we are at.”
It’s relatively uncommon for a head coach to speak about xG, but it’s reasonable to suggest that Lampard has a point once delving deeper into Chelsea’s fortunes.
xG is a performance indicator. The metric offers an insight into the likelihood of a shot being scored by considering aspects such as difficulty and location, and it tends to provide an accurate summary of whether a team deserved fewer or more goals based on their shots.
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A shot taken by Willian from 40 yards, for example, may have an xG value of around 0.01, and that’s because that shot may find the net once in 100 attempts. A penalty kick, by contrast, may be valued at 0.76 xG, as those tend to be scored roughly 76% of the time.
Once a match concludes, the xG scores tend to paint a fairly accurate picture of how the match transpired in terms of which outfit generated the best shots to win the contest.
There are various xG models, and each one will value certain shots differently. However, according to a highly sophisticated model that’s commonly used, Chelsea are third in the Premier League for xG.
The Blues have been expected to find the net 42.9 times based on the shots they have generated this season, which is bettered by only Manchester…