Agree would rather use 17 in the ND. This is what happens when your list management tries to please the enemy like this.
Astbury for 21 --> trade for Yarran.
If we're trading pick 31 for 17 let's go to the draft and pick up a KPP or ruckman. One of these blokes maybe (from 2015 draft thread, cheers one-eyed):
19. Kieran Collins ...... Key Defender (194cm, 100kg, Dandenong Stingrays, Vic Country)
20. Harry McKay ........ Tall Forward (200cm, 95kg, Gippsland Power, Vic Country)