Also, you are WAY too focused on Trump's Iowa margin having been +9 instead of the fact that he only got 51% of the vote. Ted f**king Cruz only got a 0.2% smaller percentage of the vote in Texas in 2018 than Trump got in Iowa in 2016.
To ignore the inconvenience of high third party vote in 2016 and to just say 'this candidate only got ___ percentage" is not a good argument. There was about 8% third party vote in 2016, 5% of it went to Johnson, McMullin, and Castle (constitution), it's bogus to think the vast majority of that will go to the Democrats.