The German has never known the kind of crisis mode that now grips Old Trafford and if Steven Gerrard has anything to do with it over the next two games then things will only get worse for him within the Theatre of Dreams.
Rangnick appeared the right call to take over when Ole Gunnar Solskjaer was sacked. As an esteemed technocrat of football and considered as the godfather of modern German football, his nickname is The Professor.
Sure enough, give him a clip board and a stop watch, or hand him a spread sheet of stats, he will produce the kind of analysis that would sit perfectly in a coaching manual.
What he lacks is the human touch.
Insiders at United’s massive Carrington training complex reveal that he was a month into the job before raising his head to anyone after he had collected his coffee each day from the canteen then made his way back to his new office.
Rangnick is an academic and his philosophies have guided the likes of Jurgen Klopp and Thomas Tuchel.
Yet the theories that gave him his reputation are already getting old.
Klopp, famously, utilised the ‘gegenpressing’ tactics that saw Ragnick revered back in the Fatherland when he first took over as Liverpool boss.
But he realised after a couple of seasons that the idea of winning the ball back quickly as opposed to falling back when possession had been lost was too physically demanding within the intensity of Premier League football.
Now Rangnick is deploying United's players in a 4-2-2-2 and it actually comes from the history books.
Sometimes referred to as the “magic box”, “magic rectangle”, or “magic square”, it is thought to have first been used in 1950s Brazil, where Flávio Costa focused on free, fluid and improvised attacking play.
French manager Albert Batteux then used the structure in winning eight Ligue 1 titles – the most by any manager – in the 1950s with Reims and the 1960s with Saint-Étienne.
The 4-2-2-2 system was then used most prominently in South America, although the France national side won Euro 1984 using it.
The main idea is to have two sets of two midfielders working in support of two centre forwards.
More numbers, more theory – and for a United squad that has often looked dazed and confused for months – a tactic that they cannot get their heads around. Little wonder the performances are poor.
What Rangnick either failed to recognise, or more possibly was not properly brought up to speed on, was that he was walking into a vipers’ nest.
Either way Cristiano Ronaldo – one of those two centre forwards but who has lost a vital yard of pace – rules the roost following his melodramatic return to Old Trafford. His presence has put Bruno Fernandes’ face out of joint. It is said that captain Harry Maguire is not happy with the influence he is exerting.
Add that little toxic cocktail to a collection of players not getting games and running down the clock on their contracts and you get exactly the kind of mess that now confronts Rangnick. From what we have observed he didn’t even see it coming.
United need sorting out, for sure. But by a human being, not the editor of football’s equivalent of Science Journal.
Rangnick approached tomorrow night’s FA Cup clash with Gerrard’s Aston Villa – they also meet in the league on Saturday, lecturing his players about how they need to man-up and admitting he was not properly briefed on the mood inside the camp.
It grew only worse after last week’s 1-0 home defeat to Wolves and a performance that illustrated just how badly he has failed in his attempts to turn things around and turn on the players.
“I can only tell you about the squad, I don’t know about the atmosphere inside the club,“ he said.
“The players, locker room, coaching staff, everybody was very disappointed after Wolves. All the players were frustrated, like myself.”
If Rangnick didn’t know before that he had taken over a squad that was eating itself then he does now.
Striker Anthony Martial has asked to leave, while Jesse Lingard, Donny van de Beek, Dean Henderson, Eric Bailly and Juan Mata are all frustrated at their lack of game time.
Paul Pogba, Edinson Cavani and Mata are all out of contract at the end of the season. Luke Shaw (inset) claimed the players lacked “togetherness, commitment and motivation” after that dismal defeat to Wolves.
Some players believe others get picked on name and reputation rather than form and the cliques that Solskjaer had un-picked are now tighter and nastier than ever.
Rangnick has effectively contributed to the shambles by failing to understand that just talking at players does not work these days.
A third round exit from the FA Cup, especially to a team now managed by the man who was seen by United supporters as the Scouse anti-christ of Anfield, will only pile on the pressure.
For a moment there were suggestions that Rangnick would become permanent manager.
Providing United do their business properly that will not happen because Mauricio Pochettino is now convinced that he will receive a formal approach to take over by the end of the season.
Rangnick, meanwhile, has those two further years guaranteed in his contract.
Nobody, however, will be consulting him on man management – that much is certain.