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Evolution Or Revolution – Chelsea


Evolution or Revolution is a new series from Stats Perform looking at which teams need only a few tweaks ahead of the 2020/21 season and which require a fundamental reboot. In this instalment, @Orbinho analyses the key areas for Chelsea to improve on ahead of next season. 

By: Rob Bateman

Get Clinical In Attack

Frank Lampard’s first season in charge could be deemed a success from an attacking standpoint. Only the top two scored more goals than Chelsea and only Man City mustered more shots than the Blues. However, closer examination suggests they didn’t make the most of their chances. When you look at the conversion of shots into goals, the Blues ranked 11th.

Chelsea Ranks Premier League 2019/20

The Blues’ goals scored were roughly on par for their Expected Goals, but while they netted 69, champions Liverpool scored 85 with a similar xG of 69.7. The Reds ability to convert high-quality chances, with the best conversion rate in the division, was in marked contrast to the Blues “average” performance.

Tammy Abraham top scored with 15, but highlighted a recurring issue for Chelsea; only four players have scored more than 15 league goals in a season in the last decade for the club – two of them in 2016/17 (Diego Costa with 20 and Eden Hazard with 16).

In much of the last decade, the top scorer has been a midfield player. In the two seasons listed where they had a 20-goal striker, the club won the league.

Chelsea - Top Scorer By Season

SeasonTop scorerGoalsPlayers Who Scored 10+League Position
2014/2015Diego Costa2021
2015/2016Diego Costa12110
2016/2017Diego Costa2021

The club have already acted with Timo Werner joining off the back of 28 goals in the Bundesliga last season, while Hakim Ziyech will join Christian Pulisic (9) and Mason Mount (7) as an exciting front line which Lampard will hope can provide a sterner challenge to Liverpool and Man City next season

Stats Perform Verdict: Evolution Required

Sort Out The Goalkeeping Situation

When you pay a world-record transfer fee for a player, you probably feel like you’re improving your team. That’s certainly what Chelsea hoped for when they signed Kepa Arrizabalaga for €80million two years ago. But it hasn’t worked out that way and rumours are that Chelsea are in the market for a new shot-stopper.

The Blues conceded 54 goals in 2019/20, the most of any team in the top half of the table. But when it came to Expected Goals Against – the number they would expect to concede based on the chances they faced, they were actually ranked fifth and barely any worse than the three teams who finished above them in the table.

Chelsea xG against vs. actual goals conceded

When we look at Expected Goals on Target, which shows the number of goals a goalkeeper saved in relation to the average glovesman, we can see that Kepa was ranked the lowest in the Premier League of all regular ’keepers. He actually shipped 10.6 more goals than our model suggests his counterparts would have conceded, excluding penalties and own goals.

xGOT rankings for Premier League 2019/20

Kepa xGOT shot map

Stats Perform Verdict: REvolution Required

Heading For A Fall

Chelsea’s tally of 54 goals conceded was their highest in the Premier League since the 1996/97 season. And they seemed especially susceptible to headed goals, giving away 11 during the campaign, a season-high tally since 2000/01 when the Blues gave up 12.

Headers Conceded - Premier League 2019/20

RankTeamHeaders Conceded
1Norwich City14
2Aston Villa12
4Wolverhampton Wanderers10
5West Ham United9

The 11 goals they gave up was the third-highest of any team in the Premier League and when it comes to headed goals as a proportion, 20% of all goals the Blues conceded came via headers, the second-highest in the top flight.

Headers Conceded As % Of Total Goals

RankTeam% Goals Conceded Through Headers
1Wolverhampton Wanderers25.0%
3Norwich City18.7%
4Aston Villa17.9%
5Manchester City17.1%

And it’s clear that the Blues were especially susceptible from corners. Only Norwich City (12) conceded more goals from corners than Chelsea (10) and Frank Lampard’s side conceded more headed goals from corners than any other team. What he wouldn’t give to have someone like John Terry marshalling that Blues defence today.

Headers Conceded From Corners

RankTeamHeaders From Corners
2Norwich City5
3Aston Villa4
3Manchester United4
3Wolverhampton Wanderers4
Stats Perform Verdict: REvolution Required

Review other pieces in this series:
Manchester United
Manchester City
Tottenham Hotspur
Leicester City
Leeds United
West Brom

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