It's not just positional, I think it is inconsistent players/lack of squad depth.
Lingard - has played very poorly for a few games again, doesn't know how to defend/doesn't care about defending (he let Newcastle's score run right past him). I don't know if he plays well for a few games and it all goes to head and he stops trying, or if he is just going to be a hot and cold player. Either one is not good, but it's too often now where he will disappear in games. He should not be considered a starter.
Martial - he has so much skill and pace, yet barely uses it. Yesterday, he was out on the right but how many did he take on his man outside and cross? None, despite knowing he could out run his marker as he did for the chance at goal. He cuts inside, where there is traffic, and kills opportunities because he tries to hard. Did anyone else spot Sanchez telling to him to calm down? That says a lot. The other players know he gets flustered.
Young/Shaw - Young has a few good games, gets suspended. Shaw comes in and does really well, to the point where Jose says he deserves a new contract and will be at Utd for many years, and then immediately drops him for the next game. Why? What mind games is that? And Young has now gone off the boil.
McTominay - You're 1 nil down and need to score, and you bring on McTominay? That shows how lacking in real squad depth we have.
Tactics - we'd spent the majority of the match trying to play through the back line and it wasn't working, but there was no plan B. If Jose's tactics don't work he doesn't seem capable of switching it. He said post match they could have played for 10 hours and not scored and it's true, because he would have played the same way for 10 hours! Good managers have plan B's ready to go when plan A doesn't work.