I would say that China has been massively productive but not so much in producing commodities. That means the demand for commodities has gone up much more rapidly than the supply. You could imagine an alternative universe in which China grew by figuring out ways to produce oil, copper, and rice much more cheaply. Of course that's not what happened and it is relatively easy to see why not. Following some good policy changes, Chinese growth has been driven by a massive rural to urban migration and yes we are talking about hundreds of millions of people. It's plastic basketballs that have become cheaper, not the products of farms.
The mere addition of labor inputs to urban areas doesn't, in the short run, help you produce commodities more cheaply. Think of the Solow model where K and L have gone up lots but the rate of generating new ideas is only slightly higher.
When all those new Chinese engineers and scientists are at the peak of their creative powers, this relationship will reverse itself and commodities prices will plunge. But it's quicker to produce another toy than to bring about a new Green Revolution, so in the meantime commodity prices are very high. I give the current price trend another ten or fifteen years or so to run. Eventually high commodity prices will seem permanent and then the bottom will drop out.
We've never had a rapid and successful migration of hundreds of millions before, ever.