Fast-forward two weeks. The Blues are again displaying themselves as tough visitors by dominating the possession at the Craven Cottage. The scoreline is null-all. Higuain ends up with a critical pass. But here, despite being under the press, the striker scores. Its Fulham 0-1 Chelsea now. And that doesnt stop there. Chelsea would go on to win this game and afterwards too eventually land the third spot in the Premier League table.
Its clear that Chelseas likelihood to score goals increased substantially during the latter half of the season. Mining the numbers, Chelseas expected goal (xG) statistics, which can provide a reliable way to judge the quality of shots by assessing their likelihood of becoming a goal, increased during the seasons final third particularly after the Premier League second round fixture against Fulham. Before the clash vs Fulham, the Blues were getting an average of 1.55 xG per match; after that, they got an average of 1.77 xG per game. Furthermore, after the clash, Chelsea earned their season-high rolling average of xG, i.e. 2.1 per match. Only during the opening months of the season, Chelsea scored a rolling average higher than this when Sarriball was at a peak. Before vs Fulham Chelseas, however, the highest xG could only hit up to 1.75.
The composition of Chelseas xG
The expected goals are calculated using different xG models; each assigns different weights or values to multiple factors as per the qualitative and quantitative contribution of each in assessing the shot quality. To calculate individual players xGs the basic xG models usually include the number of shots; shot location; the in-game situation; and the proximity of opposition defenders. While to calculate the teams xG, the models add up individuals average xGs per match.
These are 17-game rolling average series of Chelseas xGs before and after their match against Fulham, depicting a comparison between Chelseas attacking quality during the middle and final thirds of the season respectively. Thanks to Chelseas improved offensive game in the seasons last third which, ultimately, increased their shot quality as their xG trendline seems to be progressing upwards compared to that in mid-third of the season.
Chelseas increase in xG aggregates the individual players’ average xGs, which improved as the football season progressed into its concluding stages and thus contributed to increasing in Chelseas xG during the period.
Below is the plot of the rolling average xG of Higuain for the final and middle third of the current season. The trendline after the Fulham match (i.e.
