That's the view of Sir Alex Ferguson's former first-team coach Rene Meulensteen, who fears what United's quiet window means for new manager Erik ten Hag.
It is nearly a decade since Fergie retired and the Premier League giants' trajectory has been a downward one since then.
The 2021/22 campaign was particularly disappointing as they recorded the club's lowest ever Premier League points total.
New boss Ten Hag has his work cut out to get Man United back challenging for the league title.
There have been plenty of transfer rumours swirling around with Ten Hag hopeful of reuniting with the likes of Frenkie de Jong and Antony - two players he coached at Ajax - while they are also said to have made a contract offer to Christian Eriksen.
Meulensteen has been slightly concerned that United are yet to conclude any deals as we head towards the end of June.
He told talkSPORT Breakfast: "It is a bit of a worry. If you look how Liverpool and City have done their business with Darwin Nunez and Erling Haaland, they have strengthened.
"United have far more work to do than that. It is a massive step up [for Ten Hag].
"He needs to get the dressing room buying into his ideas and way of work, because there are some issues there over the last season or so.
"He needs to sort that out and hit the ground running. You want players to come through the door and you want to get fans excited.
"I think the messaging from him through the media has to be important.
"They are just sliding and sliding and if I don't see really quality coming through the door.
"If Ten Hag has a similar squad to last year with the players who are left, then it will be a big, big challenge."