I do believe that Jenkinson could benefit from a run of games. I dont think he is the route of our problems. Essentially Mertesacker is too slow and Kosielny is too small. This leaves Vermaelen often working with a defender who is too small to deal with big lumbering attackers and a defender who is too slow to deal with small fast attackers.
Of course this is very over-simplified....for the benefit of a couple of posters.