Chelsea: The Blues’ defense was actually superb last season

LONDON, ENGLAND - DECEMBER 22: (L-R) Antonio Rudiger, Kurt Zouma and Fikayo Tomori of Chelsea celebrate during the Premier League match between Tottenham Hotspur and Chelsea FC at Tottenham Hotspur Stadium on December 22, 2019 in London, United Kingdom. (Photo by Michael Regan/Getty Images)
LONDON, ENGLAND - DECEMBER 22: (L-R) Antonio Rudiger, Kurt Zouma and Fikayo Tomori of Chelsea celebrate during the Premier League match between Tottenham Hotspur and Chelsea FC at Tottenham Hotspur Stadium on December 22, 2019 in London, United Kingdom. (Photo by Michael Regan/Getty Images) /

Everyone who watched the Premier League last season will tell you Chelsea’s defense was abysmal, but the numbers tell a different story.

Chelsea conceded 54 league goals last season, a record spanning more than 20 years. Questions have been raised about the Blues’ defenders and many fans are convinced the unit is as much of an issue as the goalkeeper. However, numbers show that the defense did very well; the goalkeeper? Not so much.

Too many fans have written off defenders like Andreas Christensen and Antonio Rudiger claiming that they aren’t good enough for Chelsea. These fans though, are relying on the eye test alone. The problem is the eye test is often deceiving and that’s why it should be mixed with statistics. Many people remember stand-out events. For instance, the brain would not remember all the tackles a player made, but it will remember the one that same player missed that led to a goal or near-goal.

The statistics show that Chelsea defenders painted themselves decently, compared to other top teams anyway. Statistics can reveal surprising information and while they cannot be relied on to tell the full story, they do not lie. Defending is done by the whole team, not just the defenders, and the numbers show that the Chelsea players did quite a lot defensively. This is in terms of defensive actions per game.

A closer look was taken at defensive actions by six teams: Liverpool, Manchester City, Manchester United, Leicester City, Sheffield United and Chelsea. The first five were picked because they were around Chelsea in the table, and Sheffield United because it had an impressive defense, despite finishing ninth. These teams conceded 33, 35, 36, 41, 39 and 54 respectively. Chelsea conceded 13 more goals than any other team in this group. This looks like an indictment of the Chelsea defense, but a closer look shows that is far from the truth.

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According to SofaScore, in terms of interceptions per game, Chelsea leads the rest of that group at 12.1. The other teams ranks as follows: Leicester (11.1), Sheffield (11), Manchester United (9.9), Manchester City (9.3) and Liverpool (9.3). In isolation, these numbers don’t mean much, but a team that generally has a high number of interceptions should need to tackle less in theory. Chelsea, however, lead every other team in tackles per game (16.8) except for one: Leicester City (19.5). The other clubs put up lesser numbers; Sheffield United (16.1), Manchester United (15.3), Liverpool (14.5) and Manchester City (13.5). This may just boil down to the average possession that the teams had, but it could be something more. Teams that have more of the ball generally need to make less tackles.

In this regard,  Manchester City logically makes less tackles per game than any other team because the Citizens have more possession than all of their competitors (62.6 percent) with other teams having 59.6 percent (Liverpool), 57.9 percent (Chelsea), 55.1 percent (Leicester), 54.6 percent (Manchester United) and 44.4 percent (Sheffield United) of the ball. Manchester City and Liverpool are the teams that rank accordingly in the tackling chart, being the bottom two tacklers of the group, but Chelsea should then be third bottom, instead the Blues are second highest. This shows that the Chelsea players made more tackles compared to even Sheffield United, who had 13.5 percent less possession than the Blues per match.

Shots allowed per game is an important statistic, as well. Of the group, Sheffield United and Manchester United trailed the pack in shots allowed per game 11.3 and 10.3 respectively with Manchester City and Chelsea leading the pack at 7.4 and 8.5. Therefore, it is surprising that Chelsea conceded 1.42 goals per game while Manchester City let in 0.92 goals per game. Chelsea even allowed less shots per game than the best defense in the league Liverpool (9), though Liverpool allowed 0.87 goals per game. In all the three defensive actions viewed so far, the Blues come out ahead of Liverpool in every one.

Clearances per game is a statistic that is also heavily dependent on many factors; namely strength of the opposition, playing style and how often a team is under pressure. Manchester City had less clearances per game (12.5) naturally because Pep Guardiola’s playing style demands that his team play short passes wherever possible. Liverpool and Chelsea rank the same at 15.4 and Sheffield United non-shockingly leads the pack (23.2).

This is a statistic that might surprise many, but in terms of errors leading to shots throughout the season, Liverpool trailed the pack (20); six more than the second worst in Manchester City (14). Chelsea is the third best (11) while Manchester United leads the pack (7).  So far, it is clear that the Blues made more tackles than many teams around them, despite having a sizable amount of the ball, more interceptions than any team around them and allowing less shots than almost all teams near them.

Something that could explain the high number of tackles and interceptions could be Chelsea losing more possession per game than any other team in this group (10.9 times) compared to Liverpool (8.1) and Manchester City (9). This isn’t particularly an indictment on the defense either. Seeing as the Blues had a very young attack and midfield last season, they were working on their decision making, as well as adjusting to life in the Premier League.

Knowing what we do now, how come Chelsea conceded much more goals than teams around them, despite not lacking in defensive actions? “Woah! Not so fast! That’s team statistics, what about the defense? Weren’t we talking about the defense?” Fine, let’s talk about the defense.

Analyzing the defense has proved to be more complicated because teams like Manchester City, for instance, did not have a stable defense. So, Guardiola kept pushing players around to come up with a back line that could work. Nonetheless, four players were selected for every team under the microscope. Two centerbacks, one left back and one right back. For Sheffield United, it was three centerbacks, a left wing-back and a right wingback.

For Chelsea, it was also not very easy because Frank Lampard kept changing the personnel for the back line, making it difficult to select a core. But the players with the most minutes in those positions were selected and therefore, it was Kurt Zouma, Christensen, Marcos Alonso and Cesar Azpilicueta. The same defensive actions are analyzed for these defenses, using the average of their individual defensive actions.

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The Chelsea defenders averaged 1.6 interceptions per game, more than every team in the group including Liverpool (1.2), Manchester United (1.4) and Manchester City (0.9). Sheffield United would be expected to lead this statistic, especially since the Blades didn’t have much of the ball. Chelsea comes joint-second with Manchester United in tackles per game (1.7), with Leicester City leading the pack (2.3) mainly thanks to Ricardo Pereira. Liverpool trails the rest with just 1.1.  Leicester defenders also lead in clearances per game (3.4), while Manchester City finishes last (2)—Chelsea ranks fourth with 2.6.

Chelsea had many problems with set pieces last season and therefore, percentage of aerial duels won per game was an area of particular interest. Blues defenders not only contested more aerial duels per game, but also completed the highest percentage of the bunch (62.3 percent). The Blues’ back line also had the third highest passing accuracy (85.8 percent) behind Manchester City (89.3 percent) and Manchester United (86.3 percent).

One thing to note is that fullbacks and wing-backs had a lower passing accuracy because they were more involved in the attack. Therefore, they had riskier passes to make each game. Proof of this is how Liverpool defenders had the most possession losses on average (16.5), but their fullbacks had the most contributions to the attack in key passes per game and big chances created in that back line. For comparison, Chelsea defenders lost the ball on average 12.3 times. It seems like the Chelsea defenders did themselves justice, especially when compared to other defenses, so why did they concede the most goals in the group? The goalkeeper.

Save percentages have been published in almost every football tweet and how badly Arrizabalaga ranks. Unfortunately, in saves per game, Chelsea also comes last—dead last. The average amount of saves per game in the Premier League last season amongst keepers with 20+ appearances was 2.9; Arrizabalaga had 1.7. That’s too far below the average for what the Blues should be getting out of their No. 1 keeper. Arrizabalaga is not being unfairly criticized for his performances last season and now we can tell that it was not the defense in front of him that was the cause of him conceding so many goals.

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Contrary to popular consensus, the Chelsea defenders were not below par last season. In fact, they were superb. However, it was the goalkeeper however that was incredibly poor. Arrizabalaga needs to show more than he has; he needs to play better if he is going to keep appearing for Lampard’s Chelsea. Chelsea’s misfortunes last season can almost be linked solely to the man between the sticks—not this year.