Just think about actual midfielders who you would give the tag "very damaging" to and his ball getting and ball use was nothing near their level, it was just good "for a ruckman". Teams were much more worried about stopping the around the ground work and ball use of Judd, Cousins and Kerr than they were Cox. In fact most teams would be happy for him to have 25 - 30 disposals if they could stop him from giving clean taps to his midfielders.
This is exactly why we need a decent ruckmen
The last time we had midfielders of any note we won a couple of flags, when you have a gun midfield you can probably get by with a mediocre ruckman
Look at our midfield it's crap, by having a decent ruckman it will compensate for our lack of mids