The GOP actually moved to the center in a lot of ways in 2016. They toned down their hawkishness, their religious conservatism, and their small-government ideology. In every area of policy, they moved to the center, and that is why they won. It was the classic Bill Clinton strategy.
Trump? Yes. GOP congressmen? Ehh no. And GOP senators did just as well if not better than Trump in most of the swing states. Rubio crushed his opponent in Florida, Johnson performed better than Trump did in Wisconsin, Ayotte and Toomey more or less performed the same as Trump in NH and PA, McCain crushed it in Arizona, Burr outran Trump in NC, Grassley far outran Trump in IA, Portman outran Trump bigly in Ohio, etc etc.
Plus the House GOP won the PV while Trump did not.
The point is that it appears as though Trump's unorthodox positions may not have been what drug him over the finish line. If anything you could argue that savvy GOP congressmen saved him and not the other way around looking at the senate results of swing states along with the congressional results.
Given that Clinton very publically targeted suburban Republicans (without much success), it seems more a case of her dragging down the whole party.
