HomeSteak some of your assumptions are off here, we've played a 4-3-3 for like the last 12 months.
We had 2 players who could cover the 6 role for Partey. One got injured (Elneny) and the other (Sambi) isn't trusted. Hence Jorginho.
In the 8 position we have 4 players for the two positions, Ode, Xhaka and then Vieira and ESR.
Numbers were never the issue, it's about adequate cover.