What a bizzarre situation. We can't score without him, with him we don't have any sort of ball control in the mid field.
Maybe it's still a net gain overall.
That has been the case with this man utd team for a long while now. He is not the only player like that. Rashford post shoulder injury has also been like that. If we go over his top scoring season where he scored 30 goals you would come to the same conclusion as for McTominay. Rashford has not been playing well for long time now, not contributing to overall team effort and even in the games where he scored it did not necessarily mean he was playing well. But we did get by with his goals so we were happy. It was papering over the cracks, thats why now when he is not scoring we are seeing all his deficiencies and how he goes missing and does not contribute much. Now compare that with the current Garnacho (and maybe Rashford pre-shoulder injury), they are/was the most dangerous contributing to everypart of team play even when they were not scoring goals. Unfortunately, goals means winning games in the immediate way but its only papering over cracks. If we want to build a sustainable type of play, we might not score many goals at first, but at least as players become more and more accustmed to possession and creating chances and team play and eventually controlling and dominating games, goals will eventually follow. But building this also takes time, and you need to have everyone on board because you are sure to loose many games before attaining that which is the most difficult. As you loose games, you also loose confidence and this may affect the psych. Such a hell for a manager and team alike.
Now the same can be said for ronaldo, he did score goals but the team was not necessarily playing well. Similar to rashford.
Now lets look at Maguire. Credit to him for being a true professional and the mentality to get back from no man's land. He has also been improving recently. Similar to McTominay, he is a very good player and has his strengths. If we play to his strength then fair enough, he is going to be a top defender but that means being a defensive minded team where we cede possession. But again he is not the way forward! We need him now since we are a shit team and his strength which is to defend is coming to fore because we are being dominated and we are second best in possession. On the other way round if we were playing a high line and we are on the front foot, unless he has sufficient cover by his fellow defenders alongside him, we will be more exposing his limits (agility and speed).
Such a team of contradictions as someone said before.