That is exactly the point. Makele and Ndidi would make an awful partnership, as both are poor on the ball. Similarly Pogba and Tielemans are poor positionally, and would not be a good partnership. Casemiro and De Jong can both do "the other job" reasonably well, and would be a really exciting partnership, potentially better than a ndidi / pogba partnership as they are easier to play against on the ball as the opposition just have to watch pogba, and in attack, the opposition only have to get past ndidi.
Roy Keane was pretty good going forward, but he often held position to allow Scholes more freedom. The less said about Scholes tackling the better. An unbalanced midfield will always cause problems, and although Fred, Mctominay, Sabitzer have their attributes, none are world class. The statistic of Casemiro, Eriksen and Fernandes all playing in the same team of played 17, won 15, drawn 2 suggests exciting times ahead. However, we clearly need better cover in each position.