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Thomas Tuchel's side have been struggling at the back of late
Thomas Tuchel's side have been struggling at the back of late

Richard Jolly: What has happened to Chelsea's defence?


Maybe Jose Mourinho was starting to get nervous. One of his greatest records looked under threat.

Mourinho’s Chelsea team of 2004-05 conceded a mere 15 league goals. After 12 games, Thomas Tuchel’s Blues had only let in four, and two of those were penalties. They were setting a record-breaking pace.

Not now. Chelsea have conceded seven goals in four league games, with five in the last two. Include the Champions League and they have let in eight goals in three matches.

Until then, only Sam Allardyce’s West Brom had scored three or more in a game against Tuchel’s Chelsea. Then West Ham and Zenit did it in successive games.

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Were Chelsea just overperforming?

There are two contributing factors. One is that Chelsea’s defensive record was artificially good at the start of the season, partly due to Edouard Mendy’s goalkeeping; they were not quite as superior as the statistics suggested. But they have afforded more and better chances of late.

Two of the highest xGA (expected goals against) figures in Chelsea league matches have come in the last three: Leeds’ 1.92 and West Ham’s 1.71 (though Liverpool’s 3.35 and Brentford’s 2.16 are higher than both).

In all competitions, it is three of the highest, with Zenit St Petersburg posting an xG of 2.22 in the Champions League last week.

It is affected by penalties, with both Manuel Lanzini and Raphinha scoring from 12 yards against Chelsea.

But other chances tell a tale: Joe Gelhardt’s equaliser for Leeds had an expected goals value of 0.51. Jarrod Bowen had a chance with an xG value of 0.46 for West Ham.

The Hammers actually prevailed due to lower-quality chances: Bowen scored from a shot with an xG value of 0.04 and Arthur Masuaku with a cross with an xG rating of 0.01. Zenit created four chances with an xG rating of at least 0.32, scoring from two of them (plus a shot with a value of 0.05).

And in those first 12 Premier League games, besides the two penalties, Chelsea only conceded one of each: one clear chance (Burnley’s Matej Vydra, with an xG rating of 0.53) and one half-chance (Manchester City’s Gabriel Jesus, with an xG of 0.10).

Both, in their own way, are remarkable. Liverpool had five chances with an xG rating of at least 0.30 but only scored from Mohamed Salah’s penalty. Brentford captain Pontus Jansson had an opportunity worth 0.51 but did not score.

WHAT IS EXPECTED GOALS? USE xG TO INCREASE PROFITS IN FOOTBALL BETTING

How good is Edouard Mendy?

It shows Mendy’s early-season excellence.

Even with Chelsea conceding more than their xG in each of their last four league games, they still have a post-shot expected goals (based on how likely the keeper is to save a shot) of +1.4 for the entire season; in other words, he has saved almost two more goals than he should.

Only Manchester United (+6.5, thanks to David de Gea) Wolves (+6.3, thanks to the quietly excellent Jose Sa) and Brighton (+1.6 via Robert Sanchez) fare better.


What is Post-Shot xG?

  • Post-Shot xG is calculated after the attempt on goal has been carried out, if the goalkeeper is required to make a save. It takes into account the quality of the shot the keeper has faced.

This season, Martinez has allowed three more goals than would have been expected based on the attempts faced, with a PSxG difference (PSxG - Goals) of -3.1, making him the third worst keeper on that metric through 11 games.

But it worth noting that Chelsea’s xGA for those first 12 games, when they conceded just four, was 13.52. It is now 18.9, far higher than City’s 10.6.

Other statistics suggest that Chelsea have the third finest defence. They have the third best xGA, have faced the third fewest shots and, excluding penalties, they have faced 49 attempts on target, to Liverpool’s 42 and Manchester City’s 31.

They have won three games (Villa, Watford and Brentford) when they have had fewer shots on target than their opponents, while only Crystal Palace, Norwich and Newcastle have had fewer than two shots on target against Chelsea.

The drop in Mendy’s non-penalty save percentage suggests his early-season form was unsustainable overperforming.

Prem save percentage

In eight of his first nine games, it was 100 (and 67 against Manchester City in the other). Since then, it has been 50 against Burnley and Manchester United and 33 against West Ham.

Perhaps a goalkeeper has been required more due to failings further up the field.

Issues further up the pitch

Chelsea’s pass completion rate has been under 84 percent in each of the last four games; it was over 84 in eight of the first 12. Their percentage of successful pressures has been under 30 in each of the last two matches, whereas it was over 30 in seven of the previous eight.

Most obviously, they have made three errors leading to shots in the last four games, after only making two in the previous 12. The Premier League debits two Chelsea players with errors that led to goals this season: Jorginho against Manchester United and Mendy versus West Ham.

The goalkeeper had been flawless until the last fortnight. His save percentage, excluding penalties, was 93.5 before the United game; now it is 85.1, still the best for any regular in the division.

But those early-season saves may have suggested Chelsea’s defence was better than it actually was.

Jake Osgathorpe gives his verdict on the latest round of Premier League fixtures
ALSO READ: We give our verdict on the latest round of fixtures


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