Kalidou Koulibaly to Chelsea: What will the defender bring to Stamford Bridge?
The most important summer in Chelsea’s recent history is finally starting to take shape.
Raheem Sterling is in the USA after joining up with the team, and now a surprise move for 31-year-old Napoli centre-back Kalidou Koulibaly has been completed.
Together, the high-cost signings show the ambition of the new Todd Boehly era and suggest a significant departure from the old ways, with Thomas Tuchel said to be heavily involved in the recruitment process.
Whatever the outcome in the 2022/23 season, nobody will be able to say the new owners did not back the manager and nobody will be able to say Tuchel didn’t succeed or fail on his own terms.
Fortunately for Chelsea supporters, their signings look to solve longstanding problems.
In every game through Tuchel’s tenure so far he can be seen throwing his arms forward, screaming at his players to play with more urgency and verticality. He wants line-splitting passes, aggression in every phase of play, and a tactical variety that confounds the opposition.
Clearly he gets that from Sterling, a direct dribbler whose penetrative runs in possession and constant desire to make things happen mark him out from Chelsea’s current forward options.
The likes of Kai Havertz and Mason Mount operate between the lines, creating the stodginess that saw Romelu Lukaku struggle and Tuchel frequently curse his team’s attacking structure.
But what may surprise Chelsea fans is that Koulibaly represents just as important an upgrade in this regard.
He is a defensive powerhouse, a player of tremendous strength and speed who almost always wins his individual battles (more on that later), but of particular significance to the Tuchel project are his on-the-ball abilities.
In many ways he is a direct replacement for Antonio Rudiger, albeit Koulibaly tends to carry the ball himself while Rudiger passes through the lines.
The ex-Napoli captain is in the 98th percentile for dribbles (0.74 per match) among defenders in the ‘Big Five’ leagues over the last 365 days, per FBRef, while Rudiger is in the 51st (0.19 per match).
Conversely, Rudiger is in the 95th percentile for progressive passes (4.85 per match) and Koulibaly is in the 77th (3.35 per match).
Likely to start on the right of a back three instead of in the centre as Rudiger did, Koulibaly’s trade-off of dribbling for progressive passing is no bad thing; he will often be expected to roam forward to become an auxiliary right-back when Reece James advances into the tucked-in half-space position, and he will be able to do some damage from here.
Koulibaly also amassed three goals and three assists in the league last season, making him more productive than Timo Werner, while his excellent ball-retention qualities – likely to improve when united with his international team-mate Edouard Mendy - also align with the Tuchel approach.
And so the 31-year-old looks a very good fit even before taking into consideration his defensive attributes, which is the very thing that has made him such a sought-after centre-back for so many years.
The best place to start is Koulibaly’s unusual tackling statistics.
He is in the 87th percentile for tackles (2.37 per game), making him a more prominent tackler than any member of the current Chelsea squad, reflecting his remarkable aggression and proactivity when confronted with an opposition attacker.
Again, this is exactly what Tuchel demands but so often does not receive: somebody who plays with furious energy, who wants to grab the ball and pierce the lines at every opportunity.
With Koulibaly in the team, Chelsea’s tendency to shrink a little in tough games and revert to sideways possession should diminish, to be replaced by action and – with so many tackles at the back – an increased capacity to play vertically in the transition.
To put it another way, Tuchel will get closer to his desire to play in a Germanic fashion: pinch the ball and rush forward before the opponent has time to recalibrate, using pace and dribbling to move into the final third.
Koulibaly is also very good in the air, at both ends of the pitch, and has the speed to make solid recovery tackles as well as to shift across and cover the gaps that can appear behind Chelsea’s high wing-backs.
To cap it off, Koulibaly is a much-loved figure by supporters and players in Naples, and is known for his charitable work and involvement in the local community.
There is very little for Chelsea fans not to like about the deal, even if at 31 he is perhaps a little on the expensive side - yet here, too, there is an optimistic take: the new Chelsea owners are willing to adopt a ‘win now’ attitude to transfer decisions.
There is a chance that the disruption of a winter World Cup, coupled with major changes to the forward lines of both Manchester City and Liverpool, will lower the points tally of the next Premier League champion to the late 80s again.
If that was to happen, Chelsea would only be a few big signings away from giving us the three-way battle we had hoped for in 2021/22. Sterling, Ake or Kounde, and most of all Koulibaly would be an excellent start.