Another possibility is that the unemployment rate, by itself, no longer provides a good guide to spare capacity, partly due to the flexibility of labour supply. I will come back to this idea in the discussion of inflation outcomes in Australia. The third explanation is that globalisation and advances in technology have changed pricing dynamics.
There are two main channels through which this appears to be happening. The first is by lowering the cost of production of many goods. And the second is by making markets more contestable and increasing competition. The main effect of these changes should be on the  level  of prices, rather than on the ongoing rate of inflation.