Manchester United's problem can't be solved by a simple formation change according to me. Ole tried this many times during his tenure. He tried both the three man back and five. The players just aren't comitted. They don't give their 100%. They lack the responsibility to play for the badge.
Maguire doesn't deserve to be the captain for this team. A proper team should never change for a single particular player it should be the other way around. As they say no player is bigger than the club.

Moving on to the players playing in the formation. I believe Telles just isn't good enough defensively to play as a regular. Dalot's positioning has been great but he too lacks the final ball. Sancho won't be as effective in the middle, he's a proper winger and needs to operate on the win. The solution for Manchester United is a proper rebuild, they should get more players from their academy involved and get a experienced manager. The board and the fans need to give the new manager time to get their club back to its original stature.

It's sad whats happening to this beautiful club, the board needs to sort out the problems swiftly by making proper footballing decisions.