How to inject more physicality into the midfield

We seem lightweight in the middle of the park. Cabaye, Puncheon, Flamini and McArthur are all quite small. We lack presence there. I thought about pushing Ward into midfield, but he will surely switch to right back if we sign a left back. Has Tomkins ever played defensive mid before? If so, he could also drop back in as a centre back when required; something that may be especially advantageous if we sign an attacking left back, as it would enable us to have more cover. Who else from the squad could play there, or who could we sign to do the job that Jedinak used to do for us?