Below are several excerpts only the brains of those practicing the world's most useless profession (and we are very generous with that assessment) could possibly come up with, in attempting to explain the shocking outcome of reality continuously refusing to comply with their exhaustive and comprehensive Dynamic Stochastic General Equilibrium models.
Given that policymakers seldom if ever experimented with forward guidance this far in the future, there is little data to guide them. The problem, however, is that these DSGE models appear to deliver unreasonably large responses of key macroeconomic variables to central bank announcements about future interest rates (a phenomenon we can call the "forward guidance puzzle")
But the absolute punchline you will never hear admitted or discussed anywhere else:
Carlstrom et al. show that the Smets and Wouters model would predict an explosive inflation and output if the short-term interest rate were pegged at the ZLB (Zero Lower Bound) between eight and nine quarters.This is an unsettling finding given that the current horizon of forward guidance by the FOMC is of at least eight quarters.
In short: the Fed's DSGE models fail when applied in real life, they are unable to lead to the desired outcome and can't predict the outcome that does occur, and furthermore there is no way to test them except by enacting them in a way that consistently fails. But the kicker: the Fed's own model predicts that if the Fed does what it is currently doing, the result would be "explosive inflation."