Sadly for Manchester City there is no such thing as the FA Moral Cup. "We lost but in our heads we won," was Micah Richards's take on their elimination from the FA Cup. Vincent Kompany concluded that City "were definitely the moral winners" and, when it came to the two managers, it was Sir Alex Ferguson wearing the expression of a man who had just found a dent on his bonnet and no sign of the other car.

Roberto Mancini's body language was noticeably more relaxed – at least once the subject of Vincent Kompany's red card had been exhausted. He, too, felt it represented a moral victory and, when it came to the question of what it meant for the title race, his was a long, emboldened speech about it being the day City had proved to him they had the resolve and competitive togetherness to hold off Manchester United. A few moments earlier Ferguson had been asked the same question. "No good," he said without hesitation. "It was a careless performance."

Mancini did not have a single word to say against his own team and it was unusual in the extreme, going by what has been seen so far this season and the sense that, even in victory, this is someone who is notoriously difficult to please. Mancini bristled with indignation after the 5-1 win at Tottenham Hotspur in August because he was so incensed his team had conceded a goal straight from a corner. His first comment after the 3-0 victory against Liverpool last week was to reflect on losing at Sunderland two days previously. This is a tough regime, where he is not afraid of hurting his players' feelings.

Against United, however, Mancini spoke more confidently than at any other time this season and, if it had been the other way round and Ferguson saying it, the temptation is to believe it would be translated as the beginning of the mind games. Mancini does not usually go in for these ploys but a manager with wit and know-how understands how press conferences can be used to manipulate headlines, limit the disappointment of defeat and infiltrate the minds of rivals, and he seemed to be doing all this as he reflected on City's enthralling second-half effort and overlooked some of the first-half moments that would usually have him spreading his fingers in frustration.

A more considered analysis of an unconventional, often eccentric tie will remind him that the good did not always outweigh the bad. The way, for example, Nigel de Jong, of all people, pulled out of his challenge as Daniel Welbeck hooked in United's second goal. There was Aleksandar Kolarov's vulnerability at left‑back, another indifferent performance from Samir Nasri, the wretched clearance from Costel Pantilimon that put in place the chain of events leading to 3-0 and, though it is a sensitive subject, Kompany's poor decision-making.

On the scale of two-footed tackles, Kompany's was at the lower end but anyone who lifts both feet in a 50-50 challenge is taking an unnecessary risk regardless of whether they get the ball, the opponent or thin air. The modern-day referee will construe it as reckless and, more often than not, show a red card. So why take the risk?

There is only a slim chance of City's appeal against Kompany's red card being successful and, if the decision is upheld, Mancini will have only Joleon Lescott, Micah Richards and Stefan Savic to fill the centre-back places for the next four games. Suddenly Kolo Touré's absence, away for the Africa Cup of Nations, seems just as vital as that of his brother, Yaya.

City have spent so much money on players it is not easy convincing a wider audience that Mancini has genuine reasons to worry about his squad. Yet Sergio Agüero was their only available striker against United. The substitutes' bench featured the 19-year-old Abdul Razak and another member of the elite-development squad, Denis Suárez, who had just turned 18. Mancini has said himself that, if they were to suffer the sort of injury issues that have afflicted United, the league leaders would probably be unable to cope.

United had 15 players out at one stage over Christmas and have now resorted to bringing out of retirement a player who can impose calm on a young team but whose mere presence highlights some of the other issues facing the club. The time to judge Paul Scholes's second coming will probably not be until the end of the season but, for now, United supporters are entitled to wonder what it means about the club's spending plans and, specifically, the "Glazernomics" inside Old Trafford. The nostalgia surrounding Scholes can be deceptive when the most prominent 2011 memory is of him admitting his legs were no longer up to it.

It also raises the question about whether Ferguson was simply having us on when he talked about the talented 18-year-olds Paul Pogba and Ravel Morrison being able to move up from the reserves and demonstrate that United do not need another central midfielder (answer: almost certainly yes). It was in midfield where City won the second-half battle on Sunday. Ferguson was particularly unhappy with the way his team kept possession and with good reason, given that the first rule when it becomes 11 versus 10 is to consider giving away the ball a sin.

Ferguson's anger was understandable because, 3-0 ahead at half-time, United had the chance to exact a more like-for-like form of revenge for October's 6-1 thrashing at Old Trafford and inflict far more grievous psychological damage. He may also be reflecting that, after a brilliant start to his United career, Phil Jones's form is going through an inevitable dip. The goalkeeping issue may be prominent in his thoughts, too, because Anders Lindegaard suddenly looks nervous and error-prone now he has the chance to have an extended run. The Dane has earned his place ahead of David de Gea but his performance against City suggested that the extra responsibility might have polluted his thoughts.

So Ferguson grizzled about a "ridiculous" second-half display while Mancini purred over his team's performance and said "the feeling was good". As derby defeats go, City somehow emerged with their chests puffed out – and that, more than anything, will madden Ferguson when he considers there was a genuine opportunity to leave United's neighbours with a far more harrowing postmortem to undertake.