It is difficult to think of a more decisive tactical switch in Premier League history than Chelsea manager Antonio Conte’s decision to move to a 3-4-2-1 formation in September. With the Blues trailing London rivals Arsenal by three goals to nil at the Emirates Stadium, the former Juventus and Italy head coach shifted to a three-man backline in an attempt to avoid embarrassment. He then stuck with the shape in the weeks that followed, and Chelsea won 13 matches in a row to climb to the top of the table.
They remained there for the rest of the campaign, eventually amassing 93 points to claim the championship crown in style. By the time opponents had worked the west Londoners’ system out, it was too late to stop them.
Chelsea’s reconfiguration was not only significant in terms of its impact on the title race, but also because of the effect it had on other Premier League clubs. By the time the campaign drew to a close in late May, only Burnley, Southampton and West Bromwich Albion had failed to employ a three-man defensive unit at some point in the season – a rather remarkable statistic given English football’s aversion to such a setup in recent years.
The benefits of the 3-4-2-1 – which is the variant most managers opted for, as opposed to a 3-5-2 – became clearer once Chelsea had such obvious success while using it. Three at the back can make it easier for teams to build possession from the back, which appealed to coaches who liked their teams to control the ball; the extra centre-half, meanwhile, also offered the greater defensive security that other bosses craved.
Perhaps most importantly, the formation allowed two attacking players to play as inside forwards, which suited the likes of Eden Hazard and Pedro Rodriguez at Chelsea, Alexis Sanchez and Mesut Ozil at Arsenal, and Dele Alli and Christian Eriksen at Tottenham Hotspur. Rather than operating as No.10s, where the play can get congested and the ball is often received back to goal, such attackers were able to collect possession in the half-spaces and wreak havoc while opponents tried to figure out who should be picking them up.
In turn, coaches soon realised that the best approach to dealing with such a problem was by matching up: in effect, the easiest way to deny the inside forwards the pockets of space in which they thrived was also to line up with three central defenders and two wing-backs.
As with any formation, it is the application that counts much more than the theory; two 3-4-2-1s, just like a couple of 4-3-3s or a pair of 4-4-2s, can be vastly different depending on the underlying philosophy and strategy. Given how rapidly the configuration took hold last term, though, it will be interesting to see if Premier League managers continue to keep faith with three at the back in 2017/18, or whether another formation will take hold in a similar manner.