Well, all well in theory, except Bruno will play 40-50 games a season, don't you think? No chance he will start 30 games a season.
Then the DMF Santos, being the only qualified DMF #6, would probably start more than 40 games a season, if fit and injury-free.
The rest - Mainoo, Tielemans, Mount, fight for scraps on the remaining 90-100 starting slots. And you think there is space for a 6th MF?
My point is, we have 3x #8 only 1x #6, why didn't we trade Mount for DMF in the 1st place, unless there is tactics to accommodate Mainoo-Tielemans-Bruno without being over-run in the middle.