Can't see how they justify their places ahead of Richards and Zab so far.
I'm not suggesting they are bad players or condoning anyone getting on their backs, but they are settling and should be treated like other new arrivals are/were and not treated as first choice whilst they are settling down.
Richards at right back against Arsenal, for me, and I'd prob have Zab at left back (the only thing there is that it concerns me that it asks too much of him to do anything going forward whilst playing on his 'wrong' side.
I expect Kolarov to come good eventually, especially as he has shown some promise here already, but I don't know whether anyone should pin their hopes on Boateng being a long term right back, rather than centre halve.