It has not been entirely easy as the Premier League has got going again to pick up the threads. Is that manager still on the brink? Are they in crisis or resurgent? Who’s that bloke with the beard again? Perhaps most disconcerting of all was the way Chelsea swept into a 2-0 lead against Bournemouth inside 24 minutes. Weren’t they supposed to be faltering? Wasn’t there dark grumbling about Graham Potter? Hadn’t they slipped eight points off fourth?

And then Reece James, in his first game back after the knee injury that has kept him out since early October, was forced off eight minutes into the second half. The nature of the game changed, first gradually and then suddenly. Without his thrust down the right, Raheem Sterling looked far less effective.

The impressive patterns of the first half, the sense of remorselessness, faded. In part that was down to Bournemouth coming round from their period of hibernation, but Chelsea allowed them to wake. In the final 20 minutes, Bournemouth had six shots and Chelsea two. This should not be overstated: Chelsea were never anything other than comfortable winners. But, still, it would not have taken a huge amount to go differently for those final minutes to have become edgy.

A run of three straight defeats came to an end. The most immediate clouds have lifted. Nottingham Forest away on Sunday has perhaps reverted to looking a straightforward fixture before the more serious business against Manchester City on Thursday rather than a banana skin waiting to embarrass Potter.

But the way the performance declined after James was forced off cannot be ignored, particularly given how that is a familiar pattern. Chelsea for 18 months have essentially been their full-backs. This season Chelsea have won 64% of games when James has played and only 36% when he has not. They have won 75% with Ben Chilwell as opposed to 36% without. When both play, they win 80%. But James will be out for another three to four weeks and Chilwell is likely to be out for at least a couple more weeks as he recovers from his hamstring problem.

Their best two attacking full-backs give Chelsea attacking width, the opportunity to overman in midfield. They give them drive and different angles of attack. Without them, everything going forward feels bland, predictable. Even in that first 53 minutes on Tuesday, James had two shots and put in five crosses. But his impact is not just what he does, but the opportunity his movement provides for others.

To point out that Chelsea are dependent on their full-backs is also to highlight the deficiencies elsewhere. And this is to rehearse a familiar theme: good players who are not cohering into a good squad. At centre-forward, Pierre-Emerick Aubameyang was only ever a stopgap after Romelu Lukaku did not work out. In the centre of defence, Wesley Fofana is a fine player but has struggled with injuries for 18 months, while Kalidou Koulibaly does not look the player he was at Napoli.

Fitness problems have begun to undermine N’Golo Kanté, while Jorginho needs others offering angles around him. Both are 31 and out of contract in the summer. Impressive as Conor Gallagher was during his loan spell at Crystal Palace last season, it is not clear where he fits in this Chelsea side.

Reece James in action against Bournemouth
Reece James (left) was forced off eight minutes into the second half against Bournemouth. Photograph: Ian Kington/AFP/Getty Images

None of the wide forwards entirely convince. Hakim Ziyech, for all his technical ability, lacks ruthlessness. Christian Pulisic is good at running in straight lines but only fleetingly offers more. Sterling’s decision-making has always been questionable and, although he had a decent first half against Bournemouth, he has been the most vocal of the summer signings in admitting his unease after the sacking of Thomas Tuchel. And it is the sacking of Tuchel that overshadows everything, less for the decision itself than for the way it gathers together a lot of strands of modern football.

Potter’s record at Östersund, Swansea and Brighton is exemplary. If he cannot succeed at a Big Six (Seven?) club, if certain players and a section of the fanbase cannot accept him, what hope is there for any British manager? Perhaps Potter will turn out not to have been the right man, but the unwillingness on the part of some to afford him any time – and perhaps social media whining is not representative – indicates the obeisance of a part of modern football to celebrity just as surely as the chants for the benched Cristiano Ronaldo did during Portugal’s 6-1 World Cup win against Switzerland.

That feeds into a wider issue at Chelsea and at other clubs. Football is not, despite the cliche, a simple game. It is not only about buying the best players. It is vital also to get the system right and that is complicated. Very good players can look ordinary playing the wrong way with the wrong players around them; ordinary players can be elevated by the right environment and style. The reason success so slavishly follows resources is less that the rich can buy the best than that they can afford mistakes – and almost everybody makes mistakes.

Systems are hard. They take work and time both in terms of recruitment and on the training ground. There are no quick fixes.

This is the issue to which discussions of Todd Boehly’s time as the public face of Chelsea’s new owners inevitably returns. If you understand the importance of systems, that there must be synergy between the manager and the squad, why would you let one manager oversee £250m of summer signings and then sack him within a week of the window closing?

Perhaps it was simply another manifestation of Tuchel’s capacity to fall out with directors, but the warning sign is there. Nothing Boehly has said or done, from his fascination with Ronaldo to his advocacy of an all-star game, suggests he is capable of seeing beyond celebrity to the internal mechanisms of a side.

Chelsea stand at a crossroads. One road leads to a patient building process, stability and possible success under Potter, the other to glamorous chaos. They could really do with having their best full-backs to help guide their decision.