IN-5 is a very good data point for Donnelly. It's the only district where Clinton 2016 improved on Obama 2012 performance; and it's looking even better for Donnelly this time around.
Remembering the 2016 results, it seems likely those new Donnelly votes are coming from Hamilton County, which has long been a Republican bastion (the last Democrat to carry the county was
Woodrow Wilson in 1912 against a divided GOP field), but where the local Democratic party has been noticeably gaining ground in the last few elections. Significantly, said growth is reflected pretty well down ballot: it really does seem that the county is becoming more Democratic (though the GOP is still the heavy favorite), as opposed to a one-time swing against Trump.