Antonio Conte’s 3-4-3 setup worked as a well-integrated unit last season. However, this couldn’t result in the same level of effectiveness this season. Of course, their tactical setup has been figured out, like that of every champion in their post-title season. But other than that, Blues have been facing a big issue of personnel misallocation, which couldn’t bring the same kind of cohesion as of last year. This, in turn, has resulted in their incoherent passing network due to lack of forward passing in the build-up.
What was there last year?
As the last year’s 3-4-3 setup by Blues was an integral unit, any change in the setup could disturb its balance. And that’s what happened in the current season. The cohesiveness of their formation relied on a lot of elements which included Matic’s partnership with Kante as a double pivot. The Serbian midfielder used to assure enough midfield solidity to free up other resources to go up and attack. He also made fine through passes to push the game forward.
With Matic behind his back to cover, Kante also played box to box. Then there was Costa whom the ball can be passed freely as the Spaniard was built up enough physically to get the ball out of the compact defence.
The strong defensive setup also allowed Luiz to advance up to the midfield for playmaking and distribution when needed with the remaining defensive resources cover for him at the back.
What’s been unsettled now?
Without Matic to cover at the defensive midfield now, Kante is no more playing box to box. He, in fact, has had to cover the midfield to protect the backline. The French midfielder has often been seen playing as a buffer in build-up phases so that the partner CM could go up for attack. The other central midfield options, Bakayoko and Fabregas, however, are not defensively solid and can’t play box to box either.
As Kante is reserved for defence and Bakayoko is not good in creation, only Fabregas is left as an attacking option. Yet, the Spaniard needs space and defensive coverage to optimise his creative powers as an attacking midfielder.
Eventually, there is no use of midfield to initiate attacks but only to retain possession and that too when the opponents are not pressing high up the pitch. This cause reliance on the wing-backs only to initiate attacks, else either the forwards have to drop back to use the central plane for creation or a stream of back passes is followed. Other than that, there is not much use of the central plane. This depicts personnel misallocation in the midfield.
The following picture shows the passing network of the Chelsea vs Liverpool 1-1 draw. We can see that Cahill’s flank is rarely used to initiate attacks; instead, there is a lot of circulation with back passes and no significant connection with the frontline. There are also a lot of side passes from Zappacosta to Kante from then the game kept going back to Cahill or Christensen with no forward action towards the frontline.

Next, Luiz could be used in forward passing and playmaking but as he had more defensive responsibilities now, he has messed up in defence.
Cahill is losing his form and his flaws are kept exposing. With midfield sturdiness already unprotected, the wide centre-backs, and so the wing-backs, are now more responsible to clear the attacking threats. But Cahill has mostly been slipshod in one-on-one defensive challenges allowing opponents to use his flank to threaten Chelsea’s back.
Even offensively, Cahill is not of much use. Being on the terminal side of Chelsea’s back-passing network – and being the captain of course, he is supposed to dictate forward play but he just keeps the circulation within his own half. Any pass from Courtois to Cahill is also risky as the latter is right-footed and often can’t control when facing the high press. This shows personnel misallocation at the backline.
In short, somehow the integral setup has been disturbed due to Chelsea’s personnel misallocation. This lack of integration is exposed whenever the opponents are aggressively pressing or defending with high blocks. On top of that, with no Costa, the route one or long passing would not work much. We lack specialists and physicality in our front line to carry it on.
Conte’s tactical response to personnel misallocation
The only option the Blues are left with is to work on their build-up from behind which may require personnel re-allocation to restore the coherency at least unless no strong signing is made.
After the away 3-0 defeat against Roma, Luiz has been replaced by either Christen or Ampadu. Even though Christensen has done defensively better than Luiz, he can’t dictate build-up for now. Ampadu has been good there too but again he mostly passes sideways in open play. However, the most recent tactical change seems more balanced in response to Chelsea’s personnel misallocation issue at the defence, which is a swap in positions of Cahill and Rudiger. As it is obvious, Conte wants to keep Cahill at any cost. He wants to utilise his physical strength. The skipper is now the middle centre back while Rudiger being the left centre back. Azpilicueta remains as the right centre back.
Rudiger has better defensive and passing capabilities than Cahill. Being more forward-minded and faster than Cahill, he could replicate as a mirror image of Azpilicueta at the left side both defensively and offensively. Also, Courtois wouldn’t need to pass to Cahill now and has better wide centre-backs available to initiate forward crosses and serve advanced roles.
The following screenshot from the fixture against Newcastle shows Rudiger’s (orange circle) long cross into the box, which although was cleared by the opponent running up there (grey circle), caught back just outside the box by Moses running up there (purple circle). He then dribbled it inside the box and passed to Morata resulting a goal.

The following picture compares the crossing stats and heat map of the same for Rudiger and Cahill, which shows the Frenchman is clearly better than the later.

Another change recently made to deal with personnel misallocation is Bakayoko replaced by Drinkwater as a double pivot with Kante. The two have already served together in the same role at Leicester so their partnership is promising. Drinkwater seemed better in forward distribution and in connecting defence to attack.
Even though Bakayoko has better defensive stats than Drinkwater, the later can be better partnered with Kante and can cover the backline due to his positional awareness. The English midfielder has made more interceptions per game, 6.1, than Bakayoko’s 4.7. Also, due to him and Kante as a double pivot against Stoke City, Kante didn’t have to play as a buffer and got engaged more actively in build-up than he could do with Bakayoko. Even if Kante has to play as a buffer in build-up phase, Drinkwater has enough energy to play box to box, as seen against Brighton. Against Stoke City, the duo worked well to push the opponent’s game back to their own half and induced a more forward game
Conclusion
The changes recently made to overcome the personnel misallocation issues are expected to improve the balance of the current Chelsea squad and to restore their coherency. However, the reallocation wouldn’t solve their problems in entirety. Conte has to work to prompt a more aggressive, forward passing game and a better build up to cover for the issue of lack of clean finishing or of a natural finisher, which they have been facing.