In a gripping, weirdly unpolished contest, traces of the residual class City’s veteran campaigners possess were not enough to uplift a malformed team. Yaya Touré, Vincent Kompany and Sergio Agüero tried to lead the way but did not quite have the verve to do so, nor did they have the support that they should have had from City’s younger thrusters. So far, Pep Guardiola’s City have failed to straddle two eras while meeting the highest demands. A club with vast riches, some of which were spent hiring the prestigious coach, did not imagine ending the season empty-handed.

Six years ago, in another FA Cup semi-final at this venue, Touré heralded the rise of City by taking advantage of a mistake by Michael Carrick to score the winning goal against Manchester United and book a return to Wembley for the final. He then repeated the feat, firing into the net to demolish Stoke City’s dreams and deliver City’s first major honour in more than 30 years.

One year later, following a defeat at Arsenal, City launched into a six-match winning streak that reached an unforgettable climax when Agüero struck a glorious last-minute goal against Queens Park Rangers to plunder a first title in more than half a century. The Cup win followed by the Premier League consecration were supposed to mark the beginning of an imperial age for City. But it has not quite turned out like that, even if they pipped Liverpool to another title in 2014. City have been triumphant, yes, but never dominant.

Enter Guardiola, headhunted to make the club all-conquering and beautiful at home and abroad. By his own admission, that transition is taking longer than he imagined. Part of the reason for that was evident here. The teamsheet revealed the extent to which this City is an extremely flash mish-mash, a high-end hotch-potch of a side.

Five of City’s starting lineup – David Silva, Gaël Clichy and Vincent Kompany along with Agüero and Touré – started that win over QPR five years ago, with three of them having also begun the game against United in 2011. More than half the outfield players against Arsenal, if we include Fernandinho, were of a dwindling vintage. The rest consisted of players whose best years may be ahead – Kevin De Bruyne, Leroy Sané and, after Silva retired hurt, Raheem Sterling – and the trio of Jesús Navas, Claudio Bravo and Nicolás Otamendi, whose best has seldom looked close to good enough.

City’s lineup would doubtless have been sprucer if Ilkay Gündogan, Gabriel Jesus and John Stones had been fit. But the supporters who had travelled down from the north to a neutral stadium on their opponents’ doorstep were, nevertheless, entitled to believe their team had enough quality to beat an Arsenal side suspected of being locked into an undignified and terminal decline under Arsène Wenger. The grounds for that belief suddenly look less firm. And the value of City’s new guard does not look quite so high.

De Bruyne was particularly disappointing. At 25, he is older and more experienced than Sané and Sterling. Guardiola sometimes talks about him as if the Belgian is one of the world’s great playmakers, even if, as here, the manager often deploys him out wide so that Silva can pull strings in the middle.

De Bruyne’s first notable contribution was to be nutmegged by Alexis Sánchez. In the last minute of the 90 he was booked for tripping the Chilean. Between those two telling incidents he did little to suggest he deserved to be classed with Sanchez in conversations about the planet’s best players.

Touré unquestionably belonged in that company at his peak, and here he offered sporadic reminders of the heights he once reached on a regular basis. In his prime he was one of football’s most elegant bullies, a point he made with characteristic power and finesse in the 62nd minute. After exposing Aaron Ramsey’s misadventure at the edge of the City box, the Ivorian swept a first-time pass into the path of Agüero, who served up a reminder of his own pedigree by speeding away from the last defender and flipping the ball past Petr Cech and into the net.

Touré almost scored a second for City in the 79th minute when, at the end of a move he had initiated, he struck the post with a suave volley from 25 yards.

Before that, however, Touré had been one of several City players guilty of negligence in the build-up to Arsenal’s equaliser. He stood off as Alex Oxlade-Chamberlain crossed to Nacho Monreal, one of two players that Navas had been left to fend off at the back post. Navas has a hard enough time coping with one opponent; he was never likely to handle two, and he did not.

Kompany, though withered by injury, was a lone stable presence in City’s defence, whose persistent flakiness remains Exhibit A in the prosecution’s case against Guardiola. So slapstick was the bungling that preceded Arsenal’s winning goal that Sánchez did well to stifle his laughter before stabbing home. Guardiola has brought new and welcome joy to the way City play but no more mettle, let alone a silverware upgrade.

Guardiola’s immediate task is to find a way for this team to beat Manchester United on Thursday and all but secure a top-four place. That was not the sort of battle City’s owners imagined they would be fighting after beating United in 2011.