Thomas Tuchel must gear up for a new phase to reboot glitching Chelsea

Is this a glitch? Is the system experiencing an outage? It is a temptation that is best resisted, the urge to talk about this Chelsea team as a piece of fine-point engineering, to style Thomas Tuchel as a pure systems man, poring over his data charts, banging his dials, reconfiguring the flux capacitor with a bent hairpin.

But still, something is happening here. A 3-2 defeat by an excellent West Ham at the London Stadium leaves Chelsea with two wins in their last five games, their lead at the top of the table dissipated, with a sense of the same kind of drag recurring, the same clog in the works.

Even the greatest teams have vices to wrestle with. In this Tuchel Chelsea iteration it is a tendency to become overwrought in its passing patterns, hypnotised by its own possession. It would be unfair to say Chelsea have played the same game 53 times under Tuchel: there are always shifts of personnel, and of shape, too, when Romelu Lukaku plays.

But there is also a very distinct set of patterns and, in their weaker passages, is a sense that Chelsea can get a little lost in themselves, that too many parts need to fire together to change the tempo or the emotional pitch of a game. By the end here Chelsea had 19 shots to 11, and 63% of possession, but seemed always to be building and rebuilding the same moment of pressure, like a car lost in the Stratford gyratory system, somehow always circling back to the same set of lights.

First of all, this was a wonderful win for West Ham. Jarrod Bowen was a mischievous, high-craft attacking presence, battering away at the Chelsea centre-backs like a wasp against a window pane, albeit one that would eventually be cracked open. Kurt Zouma was smart and sure-footed, despite playing most of the game in various states of agony. And Declan Rice was simply himself, easing about with that familiarly stirring upright style, the kind of gait that sports writers find irresistible, that demands words like purring and gliding, a Rolls Royce, a Bentley Continental, a magnificent snorting steer. He is a wonderful footballer, the best in his position in the league, and a key reason why West Ham remain a genuine candidate to keep that fourth spot.

As for Chelsea, there will be a temptation to blame goalkeeping error for this defeat. Édouard Mendy is probably allowed an off-day. He certainly had one. But to blame Mendy would be to shoot the messenger, to become distracted by the outcome not the process. Chelsea lost this game in the way they were always going to lose a game, prefigured in their last London derby when Mendy saved the day against Brentford.

The London Stadium was a lovely, crisp, sunlit space at kick-off, and Chelsea started like league leaders. How do they score goals anyway? Pore back over this season and the most common route is an overload on the flank, a diagonal pass, usually the width of the box, followed by a shot back across goal. That or a set piece headed directly into the goal.

It is a pretty narrow gauge through which to drive your entire attacking payload. But they keep doing it all the same. And they scored one of each here. First Hakim Ziyech’s beautiful, flat, zinging corner delivery found Thiago Silva all alone right in front of goal.

West Ham equalised soon after, gifted the goal by an appalling piece of defensive play from Mendy, who took Jorginho’s back pass and tried to trick his way out of the arc of Bowen, a career outfield player with, even by Premier League standards, notably quick, scurrying feet. Mendy was forced to drag Bowen down. Manuel Lanzini clanged the penalty into the top corner.

By half-time it was 2-1 to Chelsea. This time the diagonal pass came from Ziyech, the finish from Mason Mount, who volleyed the ball inside Lukasz Fabianski’s near post. But West Ham refused to fall away after half-time. For a while they shut Chelsea down, blocking up the flanks and denying them a real sight of goal for 20 minutes. Then they took the game away, equalising with a fine low finish from Bowen, then winning it via a shanked cross from Arthur Masuaka that fooled Mendy with its weird arc.

And in fairness Chelsea are due a ripple. There was something of the miracle plate-spinner about the run to the Champions League trophy last season, the sense of every little tweak finding the right response. Lukaku was supposed to add another layer. But it is still essentially the same setup, a temporary fix that has worked so well it has become, for now, the permanent solution.

There are missing parts, too. For all the massed ranks of Chelsea talent N’Golo Kanté is so well-suited to what Tuchel wants to do in those areas. The real absence is probably a fit, working, competent Timo Werner, an attacking player with that direct, high-speed style who doesn’t appear to be playing in a pair of wooden clogs.

The last few weeks have felt like a sea change in this team, something reaching a caesura. Time for Tuchel to gear up for stage two.