I agree an organiser is required. That's why Cunningham is so vital and it's no coincidence that he brings the best out in his partners for club & country.
However, I think that Dunne is growing in stature (cue comments about his weight!!) and although he's young I think he's looking increasingly mature and from what I've seen he's the leader in the City defence.
Is Breen really the organiser we need? I'd have thought he's more cover for O'Brien actually.
Personally I think the blanace we require in the middle of defence is a combo of a ball winner & a more mobile player,and I'd fear for a Breen / O'Brien partnership.