You already know that Tier one miners only operate tier one...

You already know that Tier one miners only operate tier one scale mines. That said, BHP bought Western Mining then divested itself of much of its nickel assets such as the West Musgrave deposit which it sold to Cassini Resources. Cassini sold West Musgrave to OzMinerals. BHP took over Oz Minerals and now BHP own West Musgrave again. But BHP have always had a knack for buying high and selling low which is why the large miners need to operate at tier one scale at the bottom of the cost curve; because of all the corporate inefficiency they encumber themselves with.