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Who should be Chelsea’s first-choice centre backs?

Statistical comparison of Chelsea’s central defensive combinations

Tottenham Hotspur v Chelsea FC - Premier League Photo by Michael Regan/Getty Images

The cornerstone to any good defence is consistency and coherence, two terms that cannot be associated with Chelsea’s backline this season. Chelsea have used a wide variety of defensive schemes and personnel but with the same result: a glut of goals conceded.

Chelsea are a work in progress and the statistics attest to this fact. Chelsea are comparable in many ways to Liverpool’s 2016-17 vintage in terms of minimizing the quantity of chances conceded at the expense of chance quality. That is, while we concede few chances per game, the chances we concede tend to be very difficult to deal with.

Establishing a first-choice centre back pairing would go a long way towards stabilizing our defence for the rest of the season. The aim of this article is to identify the pairing who are most suited to the way we play.


What do Chelsea need from the centre backs?

Being a centre back for a club like Chelsea is not easy. There are a plethora of factors to keep in mind considering the way we play.

Brighton & Hove Albion v Chelsea FC - Premier League Photo by Bryn Lennon/Getty Images

Athleticism:
Our centre backs need to be fast and agile owing to the spaces they have to cover. Under Mourinho and Conte, Chelsea typically defended deep in the hope of springing counter-attacks. However, Lampard is a coach with a diametrically opposite view on the game (based on evidence thus far) and aims to take the game to opponents.

Most games are played in the opponents’ half, with large distances between the goalkeeper and the centre backs. As common sense suggests, this makes the defence vulnerable to quick vertical passes or balls over the top. To deal with this, centre backs need to possess ample pace over short and long distances, and a sharp turning radius.

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Strength and aerial ability
As football evolves towards becoming more “beautiful”, the need for centre backs who are strong and capable in the air gets increasingly overlooked. Make no mistake about it, centre backs who are weak in the air do not thrive in the Premier League even after recent tactical advancements.

Chelsea’s defenders need to be particularly good in aerial duels and be vocal in nature due to the presence of a goalkeeper who is not good in the air or a commanding leader.

Strength goes hand in hand with aerial ability for most defenders. The ability of a defender to shepherd an opponent out of play with nothing but strength is something that is invaluable yet cannot be quantified in numbers.

As mentioned before, Chelsea’s defenders get exposed to difficult scenarios due to the attacking style of play. This leaves them facing a lot of 1-v-1 dribbling scenarios. To win these scenarios, centre backs need a combination of speed and upper body strength.

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Ability to defend space
While 1-v-1 scenarios can be dealt with athleticism, defending space requires footballing intelligence and a sharp understanding between defenders.

This aspect of defending involves a lot of minor details for which football statistics do not exist, such as the direction in which a defender’s body is turned, the ability to predict an attacker’s movements and covering for teammates.

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Ability on the ball
Chelsea seek to dominate possession and this dominance begins from the back. Chelsea have a goalkeeper who is competent with the ball and midfielders who are phenomenal at finding passes. Chelsea’s defenders need to be able to link these two.

Chelsea need defenders who can pass the ball forward without taking too many touches and with the right weight. Ideally, centre backs should be able to receive and pass competently with both feet as well.

Along similar lines, defenders must also be able to execute cross-field long range passes in order to create 1-v-1 dribbling scenarios on the wings. These long passes must be flat and must not hang in the air for too long.

The receiving ability and composure of centre backs are overlooked aspects. It is common to see defenders cornered by opposition attackers or receive the ball with multiple opponents around them. In these situations, a centre back needs to be able to think quickly and manipulate the ball to prevent the situation from escalating.

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Communication and decision-making
Centre backs need to be able to communicate with each other and understand the strengths and weaknesses of themselves and their partners. This results in avoiding situations that result in the entire defence getting exposed. It is not a stretch to say that establishing solid communication and understanding is half the work done in terms of creating a stable defence.

Decision-making refers to the actions chosen by defenders at particular junctures in time. Defenders face dilemmas almost every minute of the game, deciding whether to join the attack or stay back, whether to attempt a booming cross-field pass or keep it simple, whether to dive in or stay on feet, whether to maintain an offside line or stay a bit deeper to deal with the attacker and so on.


As you might have noticed, it is difficult to quantify most of these criteria in numbers. As far as centre backs go, statistics only give us an idea about the style of defenders and not much about quality.

Numbers can be used to identify the passing ability of defenders and perhaps parts of defending such as aerial ability but overall, the best way to judge centre backs remains to watch them play.


Kurt Zouma and Fikayo Tomori

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The numbers:

11 games played
7-2-2 record (W-D-L)
1.27 goals conceded per game
9.27 shots conceded per game
2.55 shots on target conceded per game
0.87 xG conceded per game
0.10 xG conceded per shot
0.34 xG conceded per shot on target

Positives:

  • Complementary profiles, with Zouma typically sitting deeper while Tomori defends on the front foot.
  • Have shown a good degree of understanding.
  • Both are excellent athletes.
  • Both are comfortable defending large spaces and 1-v-1s.
  • Proven performances against top teams such as Man City, Liverpool and Ajax.

Negatives:

  • Lack of ability to play out of tight spaces. Zouma is not comfortable in these scenarios and Tomori is inconsistent as you would expect from a 22-year-old.
  • Both are error-prone to different degrees.
  • Tomori’s lack of height is an issue.

Kurt Zouma and Andreas Christensen

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The numbers:

7 games played
2-3-2 record
2.14 goals conceded per game
12.71 shots conceded per game
5.57 shots on target conceded per game
1.67 xG conceded per game
0.13 xG conceded per shot
0.31 xG conceded per shot on target

Positives:

  • Both are excellent aerially and rank among the top 20 in the league in this regard.
  • Christensen has improved leaps and bounds since the turn of the year and has become a commendable progressive passer.
  • The two are our best central defenders in 1-v-1 scenarios.
  • Both are aware of their limitations and are our two best decision-makers in their position.

Negatives:

  • Neither Zouma nor Christensen is used to defending the left channel and this creates serious discomfort in that zone.
  • It follows that neither are comfortable receiving the ball as the left sided centre back.

Kurt Zouma and Antonio Rüdiger

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The numbers:

5 games played
3-1-1 record
0.6 goals conceded per game
9.6 shots conceded per game
3.2 shots on target conceded per game
0.99 xG conceded per game
0.10 xG conceded per shot
0.31 xG conceded per shot on target

Positives:

  • Both are rapid, tall and strong. In terms of pure athleticism, they are perhaps our best duo.
  • Both are capable of being front-foot defenders or dropping back.
  • Rüdiger’s ability in close spaces partially compensates for Zouma’s lack thereof.
  • Both are vocal players and help in guiding others.
  • Among our central defenders, Zouma and Rüdiger are the best from a long passing perspective.

Negatives:

  • Rüdiger is not great aerially despite his height and strength.
  • Both have a tendency to over-commit at times.
  • Both have a tendency to watch the ball and miss their marking duties.

Andreas Christensen and Antonio Rüdiger

Leicester City v Chelsea FC - Premier League Photo by Michael Regan/Getty Images

The numbers:

5 games played
1-2-2 record
1.4 goals conceded per game
7.6 shots conceded per game
2.4 shots on target conceded per game
0.78 xG conceded per game
0.12 xG conceded per shot
0.34 xG conceded per shot on target

Positives:

  • The two are our best defenders on the ball and will ensure we are able to play out of tricky scenarios with relative ease.
  • Have clearly complementary profiles, with Rüdiger acting as a front-foot defender and Christensen a more measured option.
  • Our two most experienced defenders at the top level of the game. Both of them have over three seasons of experience each in Champions League football.
  • They have played together for quite some time. From the 3-at-the-back system under Conte to Sarri’s system to Lampard’s tactics, the duo have played together in different circumstances and have struck up a positive working relationship.
  • Rüdiger is clearly comfortable on the left, meaning build-up play will be smooth(er).

Negatives:

  • Set-pieces can be a real problem with this centre back pairing, as seen against Newcastle.
  • While Rüdiger is a vocal presence, lack of organization and chaotic moments are pretty common when he plays with Christensen.

Andreas Christensen and Fikayo Tomori

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The numbers:

3 games played
2-0-1 record
0.67 goals conceded per game
5.33 shots conceded per game
1.67 shots on target conceded per game
0.5 xG conceded per game
0.08 xG conceded per shot
0.3 xG conceded per shot on target

Positives:

  • Christensen complements Tomori the same way Zouma does due to his aerial ability.
  • Tomori has demonstrated his ability to play on the left, allowing Christensen to play on the right.
  • While the sample size is small, the two have shown the capacity to understand each other’s strengths and weaknesses.
  • Both are used to defending large spaces in possession-dominant teams due to their experience under Jody Morris and Joe Edwards in the Chelsea academy.

Negatives:

  • Lack of leadership and vocal communication.
  • Due to their young age, both are prone to making mistakes and being inconsistent in general. This is something we have to bear if they play together.
  • Tomori’s lack of height and Christensen’s relative lack of pace could be a combination that athletic teams could seek to exploit.
  • Important to note that their great numbers are partly caused by the small sample size and the fact they played against Nottingham Forest in the FA Cup.

3 at the back

Tottenham Hotspur v Chelsea FC - Premier League Photo by Michael Regan/Getty Images

The numbers:
9 games played
5-1-3 record
1.56 goals conceded per game
8.22 shots conceded per game
3.22 shots on target conceded per game
1.2 xG conceded per game
0.13 xG conceded per shot
0.35 xG conceded per shot on target

Positives:

  • Additional defensive security due to the presence of another defender
  • An additional player for build-up in the first phase
  • Suited to dealing with teams with two strikers or fast wide forwards
  • A well executed 3-4-3 can create several numerical advantages across the pitch.

Negatives:

  • Greater possibility of miscommunication due to the increased number of defenders involved. The chemistry between defenders is crucial, even more so than in a 2-centre-back system.
  • Removes an attacker or a midfielder, something that can be costly against smaller or more defensive teams.
  • Against teams with one striker or no wide forwards, 3 central defenders can be overkill.
  • Increased risk of the team settling into a U-shape during buildup, resulting in poor ball circulation.

Comparison and conclusion

There is a good possibility that the constant shuffling and changing of defenders has directly contributed to the defensive frailties of the team this season. To this end, it is crucial to settle on a defensive pair for the rest of the season.

  1. Zouma and Tomori have produced some excellent results for the club and are worthy of being the first-choice pairing. Despite their relative lack of comfort in tight spaces, they are perpaps our best centre back pairing and as such, should be our primary defenders when fit and in form.
  2. Zouma and Rüdiger have momentum on their side due to strong performances against Liverpool and Everton and offer greater ability on the ball thanks to Rüdiger’s presence and comfort on the left. However, Tomori is a better defender than Rüdiger and for this reason, the Zouma-Rüdiger duo has to settle for the second spot.
  3. Christensen and Tomori is an enticing prospect, which could well become a reality in the future. However, there are questions over whether this is the right time to play them together.

Let me know if you agree or disagree (ed.note: and why!) in the comments.

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