3 at the back is largely negated by teams playin one up front, particularly If you do not have a centre back that can join in the play. That also means the other 2 have to be comfortable. Mings our most likely is tooo often babysitting the other 2 and is capable of overplaying too deep.
The problem for the whole campaign has been the defensive midfield area and I don’t think we have anyone who can fulfil that role.
Going 3 at the back unless you are addressing the problem in deep midfield is not the answer.
If Mings were to move to the left of the three then he has the ability to step out with the ball and make another body in midfield. He wasn't helped centrally with Hause playing next to him who was patently unsuited to a three man defence and playing out from the back. I think that forced Mings to take a lot more risk on the ball at times. Mings also is horrible using his right foot which got exposed the longer it went on.
The problem with going with four at the back is that our full backs particularly Targett aren't strong enough defensively.
Agreed on the defensive midfield problem and I don't think McGinn is going to help in this area either.