The English winger was signed in the summer from Borussia Dortmund in a deal worth around £73 million and many tipped him to hit the ground running in the north of England.
Unfortunately, Sancho has looked rather lost in a Red Devils jersey, the 21-year-old failing to score or assist a goal in his first 12 appearances this season.
It's certainly a concerning situation, one which begs the question; was signing Sancho a mistake?
Of course, it would be foolish to definitively answer 'yes' to that question, as it's more than likely that the London-born forward will come good at United.
Liverpool legend John Barnes is adamant that signing Sancho wasn't necessarily a mistake by United and instead believes that the acquisition of Cristiano Ronaldo could fit that label.
Barnes defends Sancho
"Sancho would have been told that he's the future, but he's now a bit-part player," Barnes told BonusCodeBets.
"The Sancho signing wasn't necessarily a mistake. Maybe the Ronaldo signing was a mistake.
"How many main men do you want, rather than having others who can compliment that. The balance of Manchester United isn't right.
"Sancho came in for £80m to be one of the main attacking players but now he's got to sit on the bench, so how can we see more from him?
"That's why I feel sorry for him, and Marcus Rashford and Mason Greenwood to a certain degree. Ronaldo and Fernandes dominate the attacking impetus of the team."
As claims about the current United team go, that's up there with the boldest we've seen.
Could the signing of Ronaldo really be a mistake?
Ronaldo has saved the Red Devils on numerous occasions in 2021/22, the five-time Ballon d'Or winner netting a late equaliser away at Atalanta in the Champions League on Tuesday evening.
Ole Gunnar Solskjaer's side would be struggling even more without the Portuguese icon, of that there's no doubt. However, you can also understand Barnes' line of thinking.
Ronaldo, who's now approaching 37 years of age, is essentially undroppable and that is seriously harming Sancho's development right now.
Solskjaer needs to find a way to keep both the present and future happy, otherwise things will start to turn very ugly at Old Trafford.