Greg,
They need to keep the hype going forward. Asset valuations are stupid high and approaching levels that are not affordable to the average income earner. They also need to raise rates in June and the only way to do this is to ensure that they are pushing the markets higher to keep sentiment moving forward. Brainard is probably the most dovish of all the board members (and likely next in line for Yellen's throne unless Mark Carney from the UK central bank takes the job). It's shocking that Brainard is now joining the agenda publicly, just Google her statement from September 2016, she was very dovish. This is a face turn like no other.
June correction is coming, this is starting to look very similar to August 2015.