It isn’t difficult to identify the point at which Manchester United’s season stopped being a procession of sweetness and light. Before their trip to Anfield on October 14, United had won nine and drawn one of their ten games in all competitions. Since the final victory of that run – 4-0 against Crystal Palace at Old Trafford – they have taken four points from four league games and scored two goals.

Four games does not constitute a crisis, and very few teams in Premier League history could have coped with Manchester City’s early season noise, but even the most ardent Manchester United supporter could argue that their team has not disappointed in the last month. Here’s a stat: United’s current total of 23 points from 11 games would have seen them fifth at this stage of last season.

What is certainly true is that results have been less disappointing than performances, with Jose Mourinho’s attack grinding to somewhere between a halt and a sludge over the last month. Sludge football does not make victory impossible, but a damn sight more difficult. Some games you win by the odd goal (Tottenham), some you lose by the odd goal (Chelsea) and some contain so much sludge that only a 0-0 is possible (Liverpool).

The figures make for as bleak reading as they have viewing. Romelu Lukaku has not scored in seven games in all competitions (but went away and scored three for Belgium) and has become an isolated figure as United sit deep. Chief inventor Henrikh Mkhitaryan has created two chances in his last four league starts combined and looks bereft of confidence and spark.

Marcus Rashford’s age and local connection may provide him with more goodwill than any other United player, but his struggles are just as marked. If Lukaku is the goalscorer and Mkhitaryan the creator, Rashford is the middle ground with pace and dribbling as a bonus. He has had three shots on target in his last seven league games, has failed to create a chance in five of his last six league matches and didn’t even manage to complete a single dribble in 90 minutes against Chelsea. Stagnancy is the appropriate description for them all.

The usual reaction to such underperformance is to request changes in team selection, and there’s clearly something in that. Juan Mata could replace Mkhitaryan, Anthony Martial could give Rashford a rest and the return of Zlatan Ibrahimovic would allow Lukaku’s workload to be eased. Yet when a group of individuals all stutter at the same time, logic suggests that it is the system itself that is flawed rather than the component parts.

There are two obvious explanations for this funk. The first of those is the absence of Paul Pogba, who sits towards the bottom of this Manchester United house of cards. Pogba’s absence impacts upon Mkhitaryan and Rashford, and therefore Lukaku too. Everything and everyone in front of the Frenchman suffers.

There’s clearly something in this theory. Pogba has started only four of United’s 11 league games this season, but only three United players have created more chances in the Premier League, three have completed more passes in the opposition half and two have completed more dribbles. Every midfield in the world would miss his game intelligence and control of match tempo.

Yet hanging your hat on Pogba as the instant solution to United’s problems is a dangerous business, particularly given his injury and apparent disagreement with Mourinho over ignoring advice from Manchester United’s medical staff. Every elite team has its brightest star, but none compiled at such expense should be quite so reliant on the availability of one player.

Interestingly, United scored 21 goals in the first five games for which Pogba was absent, winning them all; there was no obvious issue then. Another explanation is a little more uncomfortable for supporters to hear: United have struggled simply because they have faced better teams.

Mourinho’s team have taken four points from a possible 12 against the top half, and 19 points from a possible 21 against the bottom half. The top-half/bottom-half split of goals scored is even more pronounced – 0.5 per game vs 3.0 per game. Was United’s early-season form merely a reflection of opposition weakness?

Mourinho, as is customary, has his own view. As he has made perfectly clear with timely leaks about links to Paris Saint-Germain, Mourinho believes Ivan Perisic to be one of United’s key players this season, or key non-player to be exact. Lukaku is a striker who thrives upon service, and neither Rashford nor Mkhitaryan are adept crossers of the ball. The failure to land Perisic has placed a ceiling on Lukaku’s ambitions against more organised defences, or so Mourinho’s theory goes.

As a measure, Mourinho has asked his full-backs to cross the ball more than his attacking midfielders, introduced Ashley ‘the cross’ Young as an attacking left-back and even switched formation to get Young and Antonio Valencia further up the pitch as wing-backs.

In a combined 1,600 league minutes, Young and Antonio Valencia account for 33% of all Manchester United’s open-play crosses in the league this season. Yet they are restricted by defensive responsibilities and must wait for their opportunities. And so comes the sludge.

Even if Mourinho is right, he must pride himself on finding a solution long before the January transfer window permits a move for Perisic or Valencia’s Carlos Soler. The return of Pogba, probably against Brighton rather than Newcastle, must signal a change. It is far easier to drop out of form than click back into it, especially when you are playing catch-up to Europe’s form team.

United have two home matches against promoted clubs before a run of three games against Watford (a), Arsenal (a) and Manchester City (h). Those exact three fixtures accounted for three of Manchester United’s five league defeats last season. Mourinho must find the glue to secure his house of cards before violent bump becomes full-scale derailment.

Daniel Storey