However, that would apparently be a deeply simplistic and naïve interpretation.
The consensus among the pundits and rival managers is not that United are getting worse - everyone else is getting stronger.
Take their back-to-back defeats over the New Year - including a shocking home loss to a side that were 28/1 shots at kick-off.
Blackburn's win at Old Trafford was greeted as proof positive that the Premier League's competitive balance remains alive and well.
If the worst team in the league can beat the champions away from home, then all it proves is just how wonderfully unpredictable English football can be.
We were told that the clutch of enduring results over Christmas were not about title contenders' flaws, but the Beautiful Game's enduring ability to surprise and enchant us.
Newcastle manager Alan Pardew said before yesterday's game that he thought United had the best squad in the Premier League.
Did he still think so when Phil Jones was shinning the ball into his own net?
This insistence that United are not slipping looks even more hollow in light of their elimination from one of the easiest Champions League groups imaginable.
Though, of course, United's exit was put down to the new-found strength of Swiss football. Well done Basel.
United's two decades of success - and Sir Alex Ferguson's successive regenerations of his side - have made predicting their downfall a mug's game.
Ferguson has found the answer so many times, it seems ludicrous to find fault with his teams, so pundits generally don't.
All the same, I can't help thinking United's 3-2 loss to Blackburn had something to do with them having as many midfielders playing at the back (Antonio Valencia, Michael Carrick) as in midfield (Park Ji-Sung, Nani).
They had major injury problems - and Wayne Rooney and Darron Gibson omitted for disciplinary reasons - but Sir Alex Ferguson's attempts to cover for these led to some strange tactical decisions.
A midfielder, Michael Carrick, played at centre-back; a winger, Antonio Valencia, played at right-back; a right-back, Rafael, played in central midfield.
Meanwhile two central midfielders, Anderson and Paul Pogba, sat on the bench.
Ferguson's manifold successes give him virtual immunity from criticism; it's hard to take issue with a man who gets to lift the Premier League trophy most Mays.
However, any other manager - really, any - would have been slaughtered for that team selection.
It was tinkering borne from the struggle to plug the gaps with United's stretched resources.
United might still win the league thanks to the ferocious winning culture Ferguson has ingrained in the club.
But in terms of personnel they are way behind City. Tottenham have a great deal more depth and Chelsea still have more match-winners.
Compare the present crop with Ferguson's last great team, 2008's Champions League winners.
Edwin van der Sar has gone, replaced by a shaky goalkeeping committee. Cristiano Ronaldo and Carlos Tevez are history, and Paul Scholes has retired.
Injuries have prevented Nemanja Vidic and Rio Ferdinand from maintaining their magnificent partnership, while Patrice Evra's form has dipped - one of the less-publicised consequences of the Luis Suarez affair.
Even the formerly imperious Jones is looking a little bit more like David Luiz with each defensively suspect performance.
Wayne Rooney - a complementary player to the extraordinary Ronaldo in that 2008 side - now bears too heavy a weight of responsibility and his Boxing Day misadventures suggest another frustrating lapse in his professionalism.
Ferguson has always backed his side in public and bridled at the notion that they are slipping. That is as it should be.
He might not be panicking, but he must know they lack quality compared with their cross-city rivals.
He has never hesitated to make changes when necessary, and in private he must be concerned - above all with the lack of options in midfield.
The positives are that United have one more point than at this stage last season, and they are on three points behind City.
But the negatives are too big to ignore. Ferguson must act. And, given his track record, he probably will.