People fussing at the back three seem uninformed. A back three means more defensive security and extra cover for the midfielders. And one crucial aspect of playing a back three alongside wingbacks is that the RWB and LWB should be able to cover ground fast when the ball is lost and make the back three into a back five. And most importantly teams that do successfully employ a back three most often field three proper CBs. Take Italy for example, Barzagli, Bonucci and Chiellini are three out and out Central defenders. So playing LBs like Nacho and Kola in the back three should be avoided and be done only when there is an injury/suspension crisis (like the FA Cup final against Chelsea). When your proper CBs are fit and available they should always be your primary players in the back three. Which would mean that since Mustafi, Per and Chambers are all fit and available, they should've been selected in the back three ahead of Nacho. Nacho/Kola/Elneny should play in the back three only when the proper CBs are not available. So instead of blaming the 343 and the formation, the blame has to be put on the person selecting the wrong personnel for the formation to work effectively!