Headline and core inflation - no link with commodities?

From the FRBSF Economic Letter: Does Headline Inflation Converge to Core, we see that commodity prices will not often drive inflation. In reality, the headline and core inflation mix has changed.  Pre-1993 there was strong co-movement between headline and core. Inflation persistence was higher in the 70's and 80's and has fallen in the last twenty years. In the post '93 period there is not a close link. The conclusion is that inflation expectations are well anchored, but this is an observation and not an explanation. Some researchers have argued that the delink is caused by the widening employment gap. 

I would argue that the decoupling has to do with a greater focus on inflation targeting by the Fed. The Fed will keep rates within a range and not allow the headline effects to be monetized. If there is a change in Fed behavior with less focus on inflation, expectations will become more focused on headline prices. The result may be a return to the '70's. 

This delinking also explains why commodity investing has not been an effective hedge for inflation. Inflation expectations are range bound which results in a lower correlation with a basket of commodities.