He will progress the ball to someone on his inside, move into a new space and expect to receive it back, or if he has a willing overlapper, will make a choice in accordance with the run they make. His dribbling is used to make the split second of space to make the pass he wants or the quick slip into a position he wants to be in. There's no point comparing that with what Grealish does, which is a very different style.His passing is good but he doesn't take on men the way say Grealish does. Against tight defences he's more likely to pass it backwards then run at the defence and beat the defender. His style of player is closer to someone like Bernado Silva.
It's not unreasonable to think he wouldn't be as good against the tighter defences United face against the majority of teams.
Passing the ball backward rather than forward or in a manner that keeps the pressure on is most certainly not his style.
The way Sancho plays is better for unlocking low blocks than all these hard runners who actually need and want space to open their legs and rush into. A slow, probing game with constant recycling of possession is where he'd be in his element, so it's strange this idea of his game being all about acres of space and sure things has become legion.