Gixer,
China's demand for commodities from oil to steel was not gradual.
Take carbon steel specifically. Their economy spiked at such a rate that it turned the entire global supply/demand picture for steel on it's ear in a very few short months. Only when China self imposed a slow down, mainly because it couldn't continue to get the steel it wanted, at the price it wanted, have the global conditions relaxed, and only just a little at that.
Like it or not, China's economic actions have a huge impact on global supply/demand equations. Larger than any other country, IMO.