Barcelona relies on fullbacks for width so that would be Alba mostly. Coutinho joins as an attacking midfielder when he plays. When Dembele plays, he typically is more of a wide-forward on the right. But, he will make runs on either side. It is a very fluid approach.Dalot is a RB and the heir apparent to Ashley Young. But honestly, I'm not gonna blame Ole for running Young out there as he's been good for years. And do you really want to go to war with Barcelona with a just turned 20 year old Dalot as a RB? That's asking quite a lot of him as I'm not quite familiar with who runs down the left side for Barcelona.
Was Young poor, yes, but his deficiencies didn't lead to a goal against either, which is really a prime need. You need a disciplined team and United were certainly that.
You know who would look great at United? Joshua Kimmich - but that ain't happening.. I think you could do worse though then trying for Leon Bailey.