Getting 'overrun' in midfield isn't the fault of one player, especially the advanced midfielder, therefore, you must have been talking about that midfield as a whole, which as I said before, is no different to ten Hags midfield three in 18/19. Actually, the only player who would be different to that midfield is Fred.
As for Van de Beek, I understand your concerns. He may well not end up being successful here, but given that the manager who managed to make Van de Beek into one of the most promising attacking midfielders in Europe is now at United, I guess the logic of some is that he can hopefully replicate it here. I mean, you say he did nothing for 2 years but he's hardly been given a fair run.
Time will tell, and I would obviously opt for Bruno in midfield, but your initial point is void, as the Ajax midfield with Van de Beek and De Jong very rarely got overrun, if at all.