The other problem is....where is the back up? If we are now playing 1 DM and two 8/10's even if we get it working then where is plan B? Mount is out now. So it's McTominay? That's a whole different set up. What happens when Casemiro is out. McTominay Mount and Bruno?! That scares the fk out of me.
Aye, this depth/options issue would be more my concern than the first choice midfield per se.
Taking Arsenal's version of the same set-up as an example, if Rice got injured they could play Partey in his place. Or, as they did against City, play both in midfield. Or, as they did in their first two games of the season, play Partey as their nominal RB who in reality is an auxillary midfielder. They also have Jorginho still knocking around I think, another different profile of midfielder that would allow them even more tactical flexibility. And then the likes of Trossard, Fabio Vieira and Smith Rowe can play as the attacking #8s if Havertz/Odegaard are absent.
Whereas we're a lot more locked into Casemiro/Mount/Bruno. We don't have a Partey type midfielder to cover for Casemiro, let alone play alongside him in some bigger games. The closest would be McTominay, who I don't think many would be optimistic seeing play regularly. And in the AM spots once either Mount or Bruno are absent you're relying on Eriksen (who most of us like but isn't exactly the pressing machine that Mount is) or VDB (who it's safe to say has done little to instil confidence). And that's it, at least until Mainoo is back and
if he hits the ground running as an option at PL level.
Basically I'm absolutely fine with ETH trying to make the Casemiro/Bruno/Mount midfield work, I'd just be much happier if he had a safety net behind that approach.