Just as a side remark: When it comes to evaluating ex-post the information content of various indicators in forecasting exercises, Goodhart’s law is, of course, not only relevant for the real economic indicators, but also for monetary ones.
The empirical evidence of a flatter Phillips curve is a phenomenon that has been documented for several economies, including the United States and the euro area (see, for instance, BIS (2006)). But as also stated by Mishkin (2007), the main reason for this is arguably monetary policy having been more successful in stabilising both inflation and output.