I agree - I think close to all of the DEM crossovers go for Trump. I speculate that the number of DEM crossovers is affected by how close the Clinton-sanders race is perceived to be. If that race is close, the DEMs vote in the DEM primary. In Pennsylvania, Clinton is blowing Sanders out of the water.
The Dems who don’t like Hillary and find Sanders too socialist have already decided to go Trump. This is an open primary and the ARG poll shows very few undecided voters, unlike the previous polls who had from 13-22% undecided. They are breaking for Trump.