With a terrible midfield the defense will have too much possession and will be exposed more, while the attackers will be isolated and won't see much of the ball, hence both the defenders and the attack will look 10 times worse than they are.
With a great midfield even average defenders and attackers will look solid and much better than they are.
Only the midfield can make the other parts of the team look much better or much worse than they are.
Unfortunately, our midfield is terrible and it's inexplicable how we didn't fully concentrate on this part of the team this summer.