I guess I'm in favor of having a dynamic team when players do different things and can fit different roles. Wingers should run back, but I don't think they are required to play any defensive football whatsoever. I can mention Barcelona players, but I will be told how they play possession football, which is true. But there are some other clubs (Real) that play very offensive and yet do very well. They can field Di Maria, Ozil, Ronaldo, Xabi, Kaka or Benzema and they will do great (only different approach against crazy Barca). Yet some would say how their defense is amazing and how they defend great but they have Marcelo as their left back, somebody who's claimed to be awful in defense. To sum it up, I think defensive roles and their movement is vital for organization of the whole team, but midfield should have more freedom. DMs are becoming a past IMO, as box-to-box players are having more vital role nowadays I think, which is another good point how to focus central midfield. But when I see this:
GK
Defensive RB - CB - CB - Defensive LB
Workrate RW - DM - Regista - Workrate LW
SS - Poacher
I feel like throwing up.