Mate, I see tanking as deliberately losing and couldnt give a rats about how it is used in the USA.
For that reason, to me, your question was ambiguous. As the question was put to me and not an American maybe you can see that.
Simple enough?
Anyway, to answer your question - Kruezer Cup in r22 2007. And to be honest, we looked very sus against the saints in the same year.
Although it can be argued, I would say that the Eagles deliberately lost games in 2010, Collingwood when they picked up priority draft picks.
They are 2 sides that made "miraculous" climbs up the ladder in subsequent years.
It appears you think the Demons are the only side to have this culture. I dont agree.