Chelsea has been reborn a bit under Thomas Tuchel’s 3-4-2-1. Tuchel understands the benefits of the formation in regards to this Chelsea squad. The formation is obviously more solid at the back, being able to shift to a 5-4-1 in the defensive phase. Furthermore, a three man line of centerbacks is nearly counter proof because there is always a spare man that can either win the ball back or delay until reinforcements arrive. More players are also available to press ahead of this stable base. Not to mention, the formation is naturally more direct with its point of possession low in the shape, freeing up attackers for runs in behind or into space.
There is one issue Chelsea has with it though. The squad is very much built for four at the back. Whether that was the intention or not, Frank Lampard recognized that he simply had too many players in certain roles to justify three at the back this season. Tuchel went a different way with it and its worked, but there are many players that now will be asking themselves how they fit in if they fit in at all.
The main difference from 4-2-3-1 to 4-3-3 to 3-4-3/3-4-2-1 is the profile of the attackers. In all those formations under both managers this season, the attacking band is made of five players with a base of five behind them (2-3 in a back four, 3-2 in a back three). That base can be formed in a few different ways. For example, a central midfielder could drop off to make it a 3-2 as if it were a back three, but the formation could remain a back four. The attackers, however, change quite significantly depending on whether or not it is a back three or back four.
In a back four, those attackers could be both fullbacks, the wingers, and the striker. It could also be the two central midfielders and the wingers with the strikers. Overall, the team is able to field four to five players who are primarily attackers. Back three, however, needs to reserve two of those spots for the wingbacks at all times. That can allow for a much more fluid attacking three, but three, no matter how fluid that three may be, is always going to be less than four or five.
What does this look like in practice? Take Lampard’s dual eight system. Mason Mount, Kai Havertz, Hakim Ziyech, Timo Werner, and Tammy Abraham could all fit on the pitch. In the 4-2-3-1, only one needed to be dropped to make way for the second player in the double pivot. 3-4-2-1 has that pivot automatically and wingbacks are needed, so suddenly only three true attackers are able to fit in.
Thus far, this has meant Hakim Ziyech and Christian Pulisic have missed out. Yes they have had injury issues and outside issues as well, but how do they get into a lineup where Mason Mount continues to be the team’s most valuable player, Callum Hudson-Odoi is making a play at most valuable player, Timo Werner is starting to score again, and both Tammy Abraham and Olivier Giroud are capable of scoring each time they play?
Chelsea has the same issue in the pivot. It is a vital duo in the 3-4-2-1 formation, tasked with the job of three players in moving the ball along and in winning it back. Jorginho and Mateo Kovacic have done well with that so far but where does N’Golo Kante fit in? Or Billy Gilmour? Furthermore, a two man midfield makes things harder for Havertz who had been playing in a three man midfield.
Not that a three man midfield with a back three solves the issue either. 3-5-2 has been used late on in a few games under Tuchel now, but that comes at the expense of an attacker and it was already noted how it is heavily congested with three spots. Make it two (even if some of those players end up in midfield) and it is simply moving the problems somewhere else.
But why switch now? Three at the back in any configuration, provided it has the right players, is as close to perfect as a formation might get. It is able to maximize advantages throughout every phase of play without leaving itself weak for the next phase. It requires many players that are good at one or more roles (i.e., Cesar Azpilicueta as a centerback and fullback) but with those players available there is little reason to do something different.
Tuchel has not been rotating much thus far, though his history indicates that he will. His style does as well, simply through fatigue in players. Back four solves the congestion issue but three at the back works too well right now to move away from. It’s a headache for Tuchel in a growing list of them as he settles into Chelsea management.