This 4-1 thrashing at the home of the noisy neighbours exposed not only a gulf in class but a lack of diligence among players who no longer fear Ferguson's wrath.
Specifically, City strolled through United's ranks to run up a 4-0 lead inside 50 minutes.
City were slick and powerful, authoritative and ambitious. Their front players were rampant and their defending fierce.
All the while, Antonio Valencia jogged back to defensive positions and let City's attackers work the ball around him.
On the other side, United's left, Ashley Young was abject. Marouane Fellaini, who was much too casual and moved too slowly when danger loomed, was given a nasty shock that not even Merseyside derbies prepared him for.
Behind a scrambled midfield and forward pack, Nemanja Vidic and Rio Ferdinand were taken apart by Sergio Aguero, Alvaro Negredo and Samir Nasri, while Yaya Toure and Fernandinho formed a mighty central midfield block.
The new City announced themselves with thrilling verve and power while Wayne Rooney stood up to the crosstown enemy almost alone. Rooney's performance was a thing of wonder, embellished with a sumptuous free kick that was greeted with an eerie silence. It emphasised his own great jump from outcast to indispensable.
With Robin van Persie injured and watching from the stands, United looked outgunned on the team-sheet; and so it proved as Young donated the ball to opponents, Danny Welbeck struggled to organise his feet and Fellaini and Michael Carrick were overrun. United's centre-backs cannot shoulder all the blame for the lack of midfield protection in a side who have now lost to City and Liverpool and drawn tamely with Chelsea.
As City fans sang "There's only one David Moyes", United's fans grumbled about Young and Valencia and asked why Shinji Kagawa had not started. Most of all they bemoaned a quiet summer in the transfer market and demanded to know why United's midfield was outshone by City's marauding band.
In the other column plenty point out that one of Ferguson's first Manchester derbies ended with a 1-5 caning for United, in September 1989, which sent the manager to his bed in despair. The difference of course is that Moyes inherited the Premier League champions, not a side being broken up.
Even so, feelings are now raw around the United camp.
Part of Ferguson's managerial religion, though, was that undulations in form should not be allowed to divert the club from its course. To maintain that faith, the manager must be immune from internal panic and resist outside pressure.
This is where force of personality comes into play. If the Ferguson mode still applies, Moyes will need to have motored home thinking of the flaws he has spotted and how he will correct them, rather than feeling overwhelmed by the size of the United job.
