“It all happened in a flash. We haven’t yet come to terms with it.” Massimiliano Mirabelli was talking of Milan’s astonishment at signing Leonardo Bonucci and it was a sentiment mirrored far beyond those with a direct hand in events at San Siro. Until last Friday there remained the temptation to see the Rossoneri’s extraordinary summer spend as a curiosity; a sequence of scattergun fripperies that would satisfy the club’s wealthy owners until the point of its high-profile, high-risk failure. It may yet turn out that way but the £35m purchase that so amazed their sporting director has caused the rest of Serie A, and many abroad, to sit bolt upright. Is this something more than a fantastical attempt to recreate an era that seemed to have long since passed?

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There is no way to answer that yet but the stark reality for their rivals is that Milan have probably not finished. The Bonucci deal took their pre-season outlay past the £155m mark and the arrival of the Lazio midfielder Lucas Biglia swiftly followed; no undesired sales have been necessary and the retention of the goalkeeper Gianluigi Donnarumma, whose departure seemed a certainty last month, appears equally significant.

On top of that Mirabelli, who has talked almost as freely as he has bought since formalising his role in April, makes little secret of their interest in adding to a strike force that has already seen the £33.5m arrival of Porto’s André Silva. Pierre-Emerick Aubameyang was linked with an expensive return to his former club but appears to be staying at Borussia Dortmund for now; more plausibly, Mirabelli has admitted that Andrea Belotti and Álvaro Morata are under consideration.

Moves for either would cause further consternation in Turin – Belotti’s departure depriving Torino of their biggest talent and any Morata deal bringing a player who spent two effective years with Juventus to a main rival – and perhaps in London too. If it is widely held that the Premier League has a monopoly on excess during transfer windows, then Milan are challenging that preconception; the lengths they are prepared to reach for the final piece in the jigsaw could have an effect on the plans of Chelsea and Antonio Conte, whose pursuit of a centre-forward shows little sign of ending.

Facebook Twitter Pinterest How Milan may line up for the start of the 2017-18 Serie A season

That, in itself, is significant because it is some time since Milan have been flies in the ointment at the very top end. Six years have passed since their last Serie A title and four since their most recent qualification for the Champions League. Nobody knew quite what to expect when Li Yonghong’s Rossoneri Sport Investment Lux vehicle bought the club for nearly £650m three months ago; those who thought they would merely stabilise a debt-ridden organisation before selling up appear to have been wrong-footed and the question now is how much further they will go.

“Milan are a work in progress,” Mirabelli said in an interview with Premium Sport. “We need to assemble the new elements with the old ones. We would like to win every game but our path is long, we want to open a cycle. In two or three years we hope to become an important team.”

He reiterated the value of scouting rather than signing players “via gossip” in the manner of other clubs he refrained from naming. These statements were designed to check expectations but they also, in an environment where instant gratification has become a minimum requirement, smacked of common sense. Milan’s coach, Vincenzo Montella, oversaw an improvement last season – that it yielded sixth place speaks of how far they had fallen – but will require time to mould his new tools into a unit that can challenge consistently.

Arrigo Sacchi, who benefited from Silvio Berlusconi’s money and patience in creating a late-1980s winning machine that Milan appear intent on emulating, said the “confidence and respect” of his bosses had helped him make successes of Ruud Gullit, Marco van Basten and other high-profile arrivals of the time. He suggested Montella needs the same but the pressure has certainly increased a couple of notches. The fee for Silva, a fine mover and finisher but one who arguably lacks a defining physical attribute, looks a gamble in particular while Hakan Calhanoglu, the gifted playmaker from Bayer Leverkusen, will be expected to hit the ground running after his £21m transfer despite missing the last four months of last season with a ban.

Bonucci, who will captain Milan next season, is from a higher bracket still and will be expected to hold it all together. The impact of his departure on their rivals cannot be overstated: the Juventus icon Alessandro Del Piero, quizzed by Italian television reporters about the move after playing in London’s Star Sixes tournament, could only admit that he “thought it was a joke” and “would never have thought anything like this could happen”.

Facebook Twitter Pinterest Hakan Calhanoglu, left, in action against Dortmund at the International Champions Cup in Guangzhou, China. Photograph: Anadolu Agency/Getty Images

In fact moves between Italy’s biggest hitters have not historically been uncommon but one knew what Del Piero meant. A tide that seemed to have shifted decisively away from Milan might be turning back and perhaps Li knew exactly what he was tapping into when he took over a club whose losses in 2015-16 amounted to £79m after tax. In that same season they made £95m in commercial revenue, which was more than any other Serie A club achieved despite a seventh-placed league finish.

The new owners must wait and see what Uefa, whose financial fair play regulations limit the losses clubs in its elite competitions can record, will make of last year’s parlous figures and the state of the finances this year after so much expenditure in the summer, but if they can bring back the good times then Milan still have a magnetism few other clubs in the world can match. Mirabelli might have shocked himself by attracting Bonucci but the end result may be that they finish up, at long last, exactly where they are expected to be.