Any residual patience felt towards Sir Jim Ratcliffe for early mistakes, such as not only keeping Erik ten Hag but effectively making him a first appointment by extending his contract, will be over if Ruben Amorim doesn't work out.
Even if it won't be Sir Jim's head on the chopping block - you aren't getting rid of someone who has paid more than a billion quid for 27 per cent of the club - questions would have to be asked of the executives he's appointed; Dan Ashworth, Omar Berrada and Sir Dave Brailsford.
For a variety of reasons, they have so far looked to me like a case of the blind leading the deaf.
Sir Jim, a remarkable businessman who should improve things eventually at Old Trafford, has assembled his sporting team to give him the right information in order to make good decisions. We are about to find out more about their supposed expertise when the Amorim era begins on Sunday.
Sporting director Dan Ashworth was adept at finding players on a smaller budget at Brighton and Newcastle but there is a different level of expectation making top-end decisions at Man United.
Sir Jim thought that paying a £20milion release clause for him was worthwhile. Like all expensive recruits, it is a reasonable to expect Ashworth to live up to his reputation. He's now in a market where every player coveted at Old Trafford goes up in price.
Brailsford, he of the marginal gains and head of sport at Ratcliffe's company Ineos, was the supposed supporter of retaining hapless Erik, and the purveyor of portable knowledge. I read somebody say that if you found Brailsford in bed with your wife, he'd convince you it was your idea!
As for chief executive Berrada, he was previously chief football operations officer at Manchester City, a job requiring different skills.
It's not an automatic red flag, the accomplished Manchester United CEO David Gill was initially a finance director. But working for a club which is far from philanthropic is a major shift from one owned by a Gulf state with a burning ambition to establish itself as a world force.
Nobody should be written off after one mistake but Manchester United's new broom didn't have a good summer. The decision to extend Ten Hag's deal was ludicrous, and the recruitment was also questionable.
Sir Jim and his team - even those on gardening leave - would likely have had input into the expensive signings of Matthijs de Ligt, Manuel Ugarte and Joshua Zirkzee.
I am assuming these players were bought for Manchester United per se, not Ten Hag's version. If they turn out to be pups, there needs to be some blood on the floor for that.
Surprisingly to me, neither was Sir Jim hugely impressive in a Bloomberg interview I watched. The absence of detail regarding his broader plans for United - and his endorsement of Ten Hag at that time - wasn't compelling.
It may seem pedantic to call out his reference to the Premiership when its name changed to the Premier League in 2007, but it added to the feel of lacking intricate thinking.
On the positive side, we know Sir Jim will concentrate minds. The club's spend of £180m in the last window is hardly frugal and inside the club, he has moved quickly to create a more dynamic atmosphere, making efficiencies where he may have felt people were on easy street.
The Glazers have commercial acumen but on the pitch, United have fallen off the cliff compared to their golden age under Sir Alex Ferguson as poster boys of the Premier League. It's why Amorim is so crucial.
He produced a wonderful team in Sporting Lisbon. So too did Ten Hag at Ajax, though as a personality the young Portuguese coach looks better accustomed not to wilt under scrutiny. Whereas Ten Hag metaphorically looked like a small man in a big suit, first impressions are that Amorim exudes confidence.
You can only bounce when you hit the bottom and I believe Ratcliffe's tenure will arrest the decline at Old Trafford. I don't think they will wait 26 years between league championships.
Yet as a significant football club both in terms of achievement and as a commercial engine, he doesn't want United to lose any more than they are beginning to.
Getting the best in class to support him was Sir Jim's ambition. Are Ashworth, Berrada and Brailsford the best in class, or the follies of a super-rich and successful man seduced by a burning ambition of owning his boyhood club and grasping at proverbial straws?
With that in mind, bringing in 39-year-old Amorim is a statement move that has to work for all concerned.
Managers should ignore social media sycophancy
Whatever the real meaning behind social media posts from Jack Grealish and Marcus Rashford this week, I would take it with a pinch of salt if I were their managers.
Grealish thanked Lee Carsley for bringing 'enjoyment' back to England while Rashford greeted Ruben Amorim's first day at Manchester United with a beaming smile and message of 'top session'.
Like many things in society, they can be interpreted to suit different narratives.
I once said that I care about players as much as they care about me, to Lord Sugar's amusement. In his experience, players couldn't care less about owners so that's how he took it. I could have actually meant I adored my players...
One angle on Messrs Grealish and Rashford is that they were digging out Gareth Southgate - who left Grealish out of his Euros squad - and Erik ten Hag who punished Rashford for lateness.
If I were any manager, including Amorim or new England boss Thomas Tuchel, I would put very little truck in a player's Instagram or Twitter output. The last people you ask if they are happy or not are players. They live in a culture of blaming everyone else for their own shortcomings. I wouldn't have sought their opinion of my appointments.
Amorim might feel lifted by Rashford's warm welcome but if he ever leaves the striker out, I am sure he'd receive the same treatment as Ten Hag.
I don't think the modern footballer in general is good at being accountable. A message, maybe dreamt up by their personal media team, might seem like a clever way of proving their point to an ex who jilted them but nobody should be fooled. The next manager is getting it just the same if they deem to pull up their shortcomings.
So I wasn't aggrieved on Southgate's behalf to see Grealish praising Carsley and favourably comparing his time in charge to others. Maybe Jack was just being a teacher's pet and gifting an apple for the manager who picked him. Maybe Marcus is trying to sycophantically curry favour with Amorim.
Either way, I couldn't care less. Grealish and Rashford will be judged over the next 12 months by what they do on the football pitch, not any simpering messages they put out.