The flaw with 3-5-2 is that as soon as your team loses the ball you retreat backwards into a 4-4-2, it happens no matter how disciplined your side is.Oh, so your interpretation is that the wingbacks are defenders? Yet in a 3-5-2, when you dominate possession, you effectively have 3 defenders and two additional overlapping wide players (the wing backs).
The system can be whatever you want it to be. If we are under the cosh it can be 5 defenders or altenatively, if we are dominant we only have 3 defenders. A 5 can also become a 4 if you have the right personnel, which we do have.
5-3-2 provides defensive cover but your wing backs have to work twice as hard in both directions, Barnes will not do this, you are then forced to leave out our most inform player.
I suspect BR will go for 4-5-1 and look to squeeze Maddison in, this is a mistake as it nullifies Tielemans I guess we truly are blessed with a strong midfield.