Arguably City haven&apost been this inconsistent with their performance levels since Guardiola&aposs first season in charge, when a squad unsuited to his needs were struggling to adapt to a new approach.
If that was the mitigation then, it feels like there&aposs none available now. The only transition this time is to playing with a real number nine, rather than a false one. It was a process that started well but is, strangely, starting to become an issue.
At Old Trafford they were poor in the first half, controlled the game for 10 minutes after the break and then fell apart in startling fashion. The reality is they are playing nowhere near the potential of this squad.
That is giving Arsenal the chance to build up an advantage in the title race. If it continues then the Gunners might fancy their chances in the FA Cup fourth round next week. City will certainly need to be out of their slump by the time the Champions League resumes against RB Leipzig.
It doesn&apost feel like much of an exaggeration to say City&aposs season is on the line at the moment. Play like they have done in recent weeks and they are unlikely to win anything. Something has to change – and fast.
Guardiola said in the week he had some “ridiculous” thoughts in his head for derby day, but what he actually ended up doing was picking what is probably City&aposs best line-up, even if some of the players were in on reputation rather than form.
But one intriguing tactical sub-plot was the sight of Erling Haaland dropping deep to get more involved in the build-up than he usually does. It&aposs an area Guardiola has wanted him to improve but it also felt like a very specific tactical plan for United.
There were times when Haaland would end up next to Rodri to try and get on the ball and that movement was aimed at confusing Raphael Varane and trainee centre-back Luke Shaw, giving them no obvious player to mark and creating uncertainty as to whether to follow him or not.
They often decided to let him go and with Fred man-marking Kevin De Bruyne, it usually meant Haaland&aposs movement got him into areas in the centre of the pitch where he could receive the ball in space, either laying it short to another midfielder or turning on the ball.
City were clearly livid at the decision of the officials to allow Bruno Fernandes equaliser at Old Trafford and they will continue to feel hard done by this week.
By the letter of the law it was probably the right call. Casemiro&aposs pass was intended for Marcus Rashford, who looked to run on to it initially, before getting close to the ball and leaving it for Fernandes.
Rashford wasn&apost involved in play to the extent that he touched the ball, but he clearly influenced the thinking of City&aposs defenders, and that is clearly being involved in the game.
When Phil Foden broke his Manchester derby duck in style at the Etihad in October, slamming in a hat-trick in that 6-3 rout, it felt like another coming-of-age moment in his young career.
Fast forward three-and-a-half months and the question now is what&aposs happened to Foden? When Guardiola was asked about him post-match at the Etihad after that derby win it felt pertinent that he praised his football ability and then mentioned a need to get his personal life in order to reach his best level.
Since that derby there have been just three goals for City for Foden and he&aposs started just nine of the Blues&apos 18 games since then. That includes a run of four successive starts, culminating in the Old Trafford derby, but he hasn&apost looked like the same player that was such a threat earlier in the season.
In his 57 minutes on the pitch he managed just 11 touches and only nine passes. He didn&apost influence the game at all.
One of the most surprising aspects of the team selected by Guardiola was the presence of Kyle Walker and Joao Cancelo in the full-back positions. Picking your best right-back and your best left-back for an away game at your biggest rivals wouldn&apost ordinarily cause an eyebrow to be raised, but both have been struggling in recent weeks.
Walker has been replaced at half-time in two of his three starts since the World Cup and Cancelo&aposs form has dropped alarmingly. They started together at Stamford Bridge a week and a half ago and were both hauled off at the break. City improved immeasurably after that.
After that game Guardiola praised Rico Lewis for his understanding of the right-back role and his ability to make his teammates play better, so with his side in need of a lift it must have been tempting to start the teenager. There was also a feeling that Nathan Ake would be the more secure left-back.
But Guardiola put his faith in his best players at Old Trafford, even if it might not have been justified in the last few weeks.