Did A Late Switch-Off From Shorten Cause Labor To Lose?

(Note for Tas readers and anyone else interested: Scott Bacon recount thread is here)

Nearly four months after the election, Labor and its supporters are still having great trouble working out what happened.  Ahead in the (faulty) polls for an entire term, well ahead in them for much of it, Labor managed to lose to a government that had seemingly imploded nine months earlier.  There are basically three possible explanations.  The first is that Labor should have won the election, but that at least some central parts of its policy platform were wrong.  The second is that Labor should have won the election and that its policies were sound, but it was let down largely by tactical issues.  The third, about which little has been said, is that Labor could not have won anyway.  (The idea here is that voters no longer care about governance scandals or internal party turmoil so long as they like the PM and the basic way that he is leading.)

A version of the second theory - and by the way, I don't subscribe to any version of the second theory - says that Labor's policy mix was OK but Labor was undone by spurious "death tax" scare campaigns and a massive advertising spend by Clive Palmer against Bill Shorten.  (Those arguing this tend to oversimplify things as if the United Australia Party did little in the campaign but attack Shorten.)  Adherents of this theory seem to have taken succour from findings of a recent ANU study that has been reported as finding that Labor lost because the Coalition made net primary vote gains in a volatile environment during the campaign, and also that a big part of Labor's failure to do likewise was voters switching from Labor to other parties because they became more negative towards Bill Shorten.