Johnson is collapsing and most of his support is going to Trump now
He’s gone from 14 to 7 in the last month and Clinton has not moved. It all went to Trump.
That’s the flaw in viewing this year with the same models as 2008 and 2012 - as they didn’t have a significant 3rd party presence. This one, the leader is in the mid 40s, so lots of room for shifting.
Unfortunately, this might plausibly include some shifting to Hillary as well.