The seat gain was purely due to the map, which vastly favored the GOP this time. 8 Republican Senators to 26 Democratic. Many of them in States that voted for Trump. And some of those were much closer than 2016. 2020 will be very different, and the BS McConnell is pulling will come home to roost. 12 Dem seats against 22 Rep seats. The giant gains by the Dems in Congress should tell you which way the people are going.