It was never going to be a facile process to replace Peter Schmeichel, of course. Even apparently in decline, and liable to commit the occasional aberration, how the Stretford End would embrace him if the great Dane returned to his familiar old kennel, barking at his defenders, today. But while his new club, Sporting Lisbon, may not be quite the Portuguese men of war that United represented in England, Schmeichel, at just 36, is luxuriating in the kind of haven that he has desired for himself and his family since the 1998 World Cup.
Meanwhile, the character described by Sir Alex Ferguson as "a giant figure in the history of United" could not have imagined that he would leave behind such an uncertain state of affairs at Old Trafford. It has been a case of "Come in number one, your time is up" as Mark Bosnich, Massimo Taibi and Raimond van der Gouw have all laid claim to being first-choice goalkeeper, with the season not yet four months old. Thankfully for United, a fourth candidate, the 21-year-old Nick Culkin, knows his place, having played only a few seconds of Premiership football when he came on for the injured Van der Gouw at Highbury.
After Schmeichel's eight seasons, and a total of 398 games, when any absence was almost the subject of a national debate, tabloid headlines have demonstrated all too graphically the problem of filling the goalkeeping vacuum left by the Dane: "Italian not Bos my No 1 keeper, says Sir Alex Ferguson", "I'm backing Mark to bounce back", "Raimond: Now make me the No 1", "Culkin on standby at the Bridge".
Indeed, with injury and form doubts about his principal keepers, Ferguson took all four on the midweek trip to Fiorentina as a precaution. While many teams might well consider that a luxury, it says just as much about the problem which has beset the manager. Schmeichel was not just a splendid shot-stopper and ball-handler from crosses. He was also a communicator, even though his observations to defenders were not always for those of an easily shocked disposition.
"I'm absolutely certain that all the great players I found myself playing alongside at Manchester United appreciated that their man at the back was alive and focused," Schmeichel says in his recent autobiography. "I quickly established a noisy partnership with my two good friends, Steve Bruce and Gary Pallister. I've often been accused of being the most aggressive of the three, and that may well be the case, but it was really a question of constant three-way communication." Intriguingly, he adds: "If you take my on-field presence, both visual and verbal, away from me, I would be quite an ordinary goalkeeper."
Not every goalkeeper needs to bellow like a fish-wife to be effective. But the evidence this season has been that United's defence has failed to harmonise with their goalkeeper. The lack of confidence shown by defenders in their last line has, at times, been palpable. It has meant that indecision has spread like a virus. While one can hardly chide the Premiership leaders for lack of success as they head off to Tokyo to play Palmeiras in the Toyota Cup on Tuesday, they do appear considerably more vulnerable than in recent years.
Goalkeeping is a science that has radically altered, particularly with the introduction of the pass-back rule. It is also an area that most managers - other than former custodians themselves - would prefer to leave to others. It is, after all, a specialist field of expertise.
The publicly stated view of Sir Alex Ferguson is that: "I want to see competition among the keepers at this club. It happens with outfield players, so I don't see why it shouldn't happen with keepers." That is doubtful. You dispute the theories of Ferguson at your peril, but it will be recalled that he never thought to import another keeper to put an edge on Schmeichel.
Few goalkeepers perform well when their position is under pressure. An outfield player, whose form has deteriorated, can to some extent conceal it. There is no hiding place for the keeper who knows that his manager's eyes are scrutinising him.
One suspects that, privately, Ferguson would give the royalties from his autobiography for some continuity in the goalkeeping department. Well, perhaps not. Nevertheless, it is a problem that he could well do without, yet one which shows no signs of disappearing.
It has been a bizarre season for United net-minders. Bosnich - Sir Alex's initial first-choice though he has apparently harboured doubts about his temperament - who was signed from Aston Villa and is reputedly on just under pounds 2m a year, has suffered injury problems. He has also struggled with his weight and his kicking has been indifferent.
Within a month the laid-back Australian, notorious for his "Hitler" salute at White Hart Lane and blowing kisses to crowds, had not only been relegated below the incoming Taibi, but also below the 37-year-old Van der Gouw, who had spent three years as reserve to Schmeichel. No wonder the Australian was under the impression that he had been banished to the Manchester United outback.
When Taibi, costing pounds 4.5m from Venezia, and formerly with Milan and Piacenza, arrived, Ferguson admitted: "I've got an open mind about what will happen and performance will always decide - but I'm hopeful Massimo confirms his ability and can't be moved. One of the reasons for bringing Massimo here was to see a situation develop where one becomes better than the other. I don't have any compunction about that."
Ferguson had already tried to sign Taibi as understudy to Schmeichel in February, but failed. So there was no doubting his faith in the Italian.
"The standard of keeping in Italy is fantastic, the best in the world," Ferguson declared after Taibi's first game against Liverpool. "So we have someone of a very high standard."
Unfortunately his part in United's 5-0 defeat at Chelsea and that horrendous error, allowing Matthew Le Tissier's speculative punt for Southampton to go through him like knife through jelly at Old Trafford, put him in effect at the bottom off the class, despite his protestations that there had been language problems.
"Here the pace of football is so much quicker," he said, "and there are crosses and shots coming at you from the first second to the last, whereas in Italy the build-up is much slower."
By early October all three keepers were claiming to be No 1. Bosnich is probably the most talented and most authoritative in his area and Van der Gouw the least error-prone. After that build-up even the pragmatic Sir Alex is unlikely to dispense with Taibi. The future is far from certain.
How the United manager must wish for a player like Schmeichel who is in total command of his territory. As the goalie-turned-TV presenter Bob Wilson said in describing his famous star-jump: "He leaps at attackers with two size 10s flying, two bloody great hands and a great blond thatch. Terrifying for anyone who strays inside." The trouble is, they just don't make them like that any more, do they?