I agree don't even think it needs to be drastic.
two of Bentancur, Bissouma and Saar should always start away.
Have the full backs be more traditional and when they push up, have the no. 6 drop in backline to make a 3 when in possession to negate the counter (think this would really suit Gray)
You can still have the same attacking principles with less moving parts, sometimes it's a case of working smarter, not just harder.
Being away from home in a clearly up for it stadium, misplacing passes and then having to cover huge amounts of ground time and again must have been exhausting both physically and mentally.
Also why did no one think to mark their number 11 at corners, every single corner they just floated the ball to him to fire a shot off at the edge of the area.