He should be in midfield really.
One of the few that doesnt get physically bullied in these games and can live with game deeper also in way likes of Fermin cant.
Would be a big difference if had Pedri and Frenkie with Olmo having ability to drop in closer to them and provide more options.
But Flick doesnt seem to want that. He want that second striker/AM taking risks higher up park but it leaves Barca deeper two exposed a lot.
There is an argument for saying front four of Rashford, Raph, Olmo and Yamal and being more flexible depending on what game needs.
If Yamal on edge of game.. try him in middle and put Raph RW for a bit... if opposition pressing high put Rash CF for a bit and see if can stretch them etc.
Flick is very rigid though in what wants front four to do and wont try to change it much.