Jambo, the poll that indicated that LNP would lose 30 seats with Abbott as leader was conducted in the week prior to the election. At the same time they did that poll they also asked who they would vote for with Turnbull as leader.
Well they managed to get the election result right so that gives the poll on if Abbott was leader a lot of creditability.
You under estimate how much on the nose Abbott was, he could have offered every thing under the sun but people would be remembering them of the 2013 and labor reminding them of it