Worker bargaining power must match employer power.

https://www.google.com.au/amp/s/www.washingtonpost.com/amphtml/news/wonk/wp/2018/01/26/why-cant-conservatives-just-admit-they-were-wrong-about-inflation/

Re: my (or rather the IMF's) previous work linking stubbornly low inflation in the developed world to weakening worker bargaining power (here and here). 

Unions were stronger in the 1970s, so the oil price shocks that happened then translated directly into higher wages and inflation.

Now, with less worker bargaining power, neither the oil shocks of 2008 or 2011, nor the massive monetary stimulus following the GFC, nor the current (subsequent) economic recovery and strong profit growth, has translated into strong inflation (despite the doomsday predictions of many conservative economists who perhaps were intellectually influenced by the 1970s a little too much).

Another way to look at it is that when worker bargaining power is too strong or too weak, it has made central banks' jobs harder - harder to keep price shocks from driving inflation too high in the 1970s and harder to allow positive recovery to drive wages and inflation now.

Worker bargaining power must MATCH employer power, not exceed it and not fall short.