O'Shea and Lobbe are both worth "reasonable" trade value, i.e. more than just a token pick, like pick 70.
Hampson went for 32, McIntosh went for 38, Renouf for 33, Maric for 37. Hampson and Renouf were worse than Lobbe, and while HMac at his best was pretty good, he was old and had missed quite a lot through injury when traded. Basically, even mediocre rucks go for a pick in the 30s to teams desperate enough for ruck stocks.