Not a position we need back up in - we need cover for central midfield + defence. Canners not yet fit, and we've seen the effect injury can have on the back four. If any of our back four gets injured we will struggle for cover, ditto Sleath and Church (not sure about Clarke yet).
We've got more than enough cover for the wide/forward positions. As Jason has said, it's more about cover than bringing in someone to replace a starter. Darley was ideal from that point of view as he could cover a number of positions - maybe we could try to get him back?