2nd half of the season Tippet has done as much ruckwork as Pyke. Part of that is because Pyke has been out with injury, but even when Pyke has returned Tippet's hit out numbers have been equal / higher.
I think we've looked after Sandilands a bit over the last part of the season. Against Carlton, St Kilda and GWS especially, Griffin has had more ground time (not sure what the split is with ruckwork, but Griffin about 10% more time on ground than Sandilands), and with the rest against Port, its probably primed for Sandilands to ruck 90% or more against Sydney.