Kolarov still has one of the best left foot in the business but I really believe that the only viable position for him in this team is Left Midfield and that is a stretch. Don' t think he can play left back effectively anymore (too rigid, no flexibility,no athleticism , no acceleration, especially when tracking back)and certainly cannot play center back. Maybe his technical ability with that left foot and his natural personality and leadership qualities is the reason why the manager considered him for CB or maybe because of circumstance e.g injuries and other things relating to transfers, Only Pep knows but we will find out what happens when the season starts.