I would like to make the profound observation that its what you do with your touches that counts rather than where you make them.
Lingard was asked to play an 'Iniesta' role ( albeit on the right), Matic was Busquets and Pogba is Rakitic ( albeit on the left). None of the United 3 are as good as the Barca 3, but for different reasons.
No-one has been as good as Iniesta for the last decade, so Lingard is on a loser in comparison. However he has the same basic skill sets and will improve. This is his best position.
Matic is a not quite as good as Busquets at his best, but the difference is marginal.
Rakitic drives forward from deep, but he knows how and when to pass, importantly he knoes how to keep it simple when necessary, which is often to get the best out of the attackers. Pogba can drive from deep but continually makes it 'complicated' by trying too much. When it doesn't pay off he becomes disheartened. He has to learn to keep it simple and give good penetrative passes which most of the time will be short passes designed for the attacking player to run onto. He is at least as talented as Rakitic, but does not perform regularly to the same standard because of his lack of maturity.
United have McTominay coming on nicely as a no 6, but lack competition for the two no8 positions. I would be very surprised if 2 no8s are not bought in the summer.
For sometime I thought United's attackers always stood still and waited for the ball to feet, which made attacks very static. But on anaysis , they give up making runs into space quite quickly every match, because the midfield just doesn't release the ball fast enough and in positions that allow players to run onto the pass. This is where the 'old' Fergie United teams excelled.
Both our no8s have to improve immensly in this area otherwise they will be both replaced.