The Amass case is a strange one. A natural left-back in United’s academy, who did well in a loan spell at Sheffield Wednesday last season, then got injured straight after switching to Norwich in the winter window, Amass, 19, impressed many observers with his performances during pre-season, when he shadowed Shaw.
Yet, for some reason, United were willing to let him leave.
In the summer of 2024, then manager Erik ten Hag opted not to pick the teenager in his squad for the Community Shield, even though Amass had given a creditable account of himself up against Mo Salah in a pre-season game in the United States just a week earlier.
Ten Hag felt, physically, Amass was not at the level required. In theory, the two years that have elapsed since then should have made the defender bigger and stronger.
There have been multiple expressions of interest in Amass. Even heading into deadline day, his omission from United’s Premier League 2 game against Leicester on Monday reinforced a widespread belief he would leave, probably on loan.
But that has not happened and it is not clear what his role will be within the senior squad.
The willingness to view Mazraoui as a left-back option was helped by the performances of Leny Yoro in pre-season.
Signed from Lille for £52m in 2024 as a central defender, Carrick used Yoro mainly as a right-back this summer.
Against Ipswich on Sunday, that was the slot Yoro was introduced into as a replacement for Dalot, at the same time as Mazraoui was coming on for Shaw.
At just 20, Yoro has plenty to learn about the right-back role. However, he has pace, is strong and is good on the ball. United supporters only have to look at how Josko Gvardiol has adapted to the full-back role at Manchester City after signing as a central defender to realise switching positions can have a positive outcome.
That is the calculated risk United have taken.
What they absolutely did not want to do, having taken a hardline stance all summer on the fees they were willing to pay, and a refusal to spend more than they thought a player was worth, was end up making a signing like Alex Telles, or Matteo Darmian, or Sergio Reguilon, who all arrived in recent years but were evidently short of the standard required.
It makes sense. It is probably the right call.
But that is a view taken away from the emotion of matches and the rollercoaster of results. And the reality is they will be the deciding factor in whether it was a good decision or not.