Yes, Sandi is better than just about anyone as a ruckman, but the way he spoke when he signed on for 2019, was that things would be a little fluid in terms of his own game time and his mentoring of the others.
With Lobb on the field as a big forward and Hogan and Tabs running all over the place, marking everything, why can't they simply get Lobb or Tab etc, to contest every ruck contest forward of the centre, or deeper if need be, and Darcy spend more time on the ground without having to run deep forward to contests. Sort of like the pre-rolling-scrum ruckman, hanging back-kick-behind-the-play...mopping up...and having a rest, but still a presence on the ground.