Verts is our best centre back, yet personally I feel ekotto is a weak leak in defensive sense, as is walker, but with verts at left back and kaboul in the centre, it gives us greater quality then if we have verts in centre and ekotto at left back.
This is assuming verts is happy to play at left back!
He's 2 goals in 2 games from LB isn't he? Maybe he'll love it there?
