Chelsea’s attack

There has been some buzz this week that “Chelsea are back” as an attacking force. The Blues have scored eight goals in four Premier League games since the departure of José Mourinho as manager and Diego Costa, who has scored three of those goals, has been bought by more than 70,000 Fantasy Premier League Managers this gameweek. Furthermore, Oscar, who has scored twice, has been added to more than 14,000 teams.

Is this Chelsea revival for real, or is it the latest false start this season? Undoubtedly, eight goals in Gameweeks 17-20 compares well to one goal in Gameweeks 12-15.

The chart shows, in shades of blue, Chelsea’s attacking performance in terms of shots, shots in the box, shots on target and goals over the first 20 gameweeks of this season. It also shows, in shades of red, the average number of shots, shots in box, shots on target and goals conceded per game by the opposition over the same period.

Chelsea’s goals and underlying data roughly kept track with their opposition until about Gameweek 8. After that, Chelsea’s attacking threat diminished. They rediscovered it in Gameweek 12, but at that point their goal conversion almost completely dried up until Mourinho’s final game in charge. With the departure of Mourinho, there appears to be an uptick in the number of goals scored, but nothing extraordinary relative to the opposition, except the three goals away at Crystal Palace in Gameweek 20.

Where there has been a big improvement in the post-Mourinho era has been in goal conversion rates.

Whereas Chelsea under Mourinho were converting fewer shots, shots in the box and shots on target into goals than the league average, that has completely changed around since he left – although it should be noted the sample size in the post-Mourinho era is very small.

Being a team used to competing at the top of the league, some FPL managers might expect to see Chelsea performing above the league average when it comes to conversion. The players are priced such that we should expect better performances out of them. Here is how they performed last season, when they were crowned champions.

While Chelsea’s current shot conversion rate and shots in box conversion rate is not too far off their performance above the league average last season, their shots on target conversion rate in the post-Mourinho era is looking unsustainable. Last year, Chelsea converted shots on target at 4.35 per cent above the league average. In the post-Mourinho era they are converting at 19 per cent above the league average.

Chelsea’s goal conversion may have improved since Mourinho left, but don’t expect the team to keep scoring as frequently in the long term unless they further improve their all round attacking game and consistently exceed the standards set by their opposition.