Roy Morgan polls are erratic, but the latest one seems to show a pretty simple shift, National down 3.5 and NZF up 3.5. (Overall the result is good news for the left as currently being discussed elsewhere).
I have never found Morgan’s commentary on the polls to be useful. It always looks like trying to spin “beltway” issues to account for noise. The commentary on this poll is a fine example of the effect, attributing NZF’s rise to Winston’s theatrics (ejection from Parliament, claims on a joint policy platform). Who, in the real world, knows or cares?
A straight 3.5% swap National to NZF looks to me like the impact of the flag fiasco. A chunk of conservative Key supporters got pissed off with him dissing their flag and went to the patriotic Peters. Simple.
It is often said that it takes a while for big events to have their impact in the polls, and I think those who pronounced Key “unscathed” after a poll quickly following the flag fiasco were wrong to do so. He took a (self-inflicted) hit.