Arizona demonstrates that ticket-splitting is not dead. There appear to be a substantial number of Ducey/Sinema voters. I would assume that they are independents and moderate Republicans who are satisfied with Ducey's performance as Governor and who are attracted by Sinema's centrism.
Eh, I would disagree. Ducey is really popular, so it makes sense that voters would keep him, just as voters are keeping Baker, Scott, and Hogan. The senate race seems to just be D vs R, being a bit better than 2016, with no real data showing its specifically Sinema's centrism that attracts people(especially when the R campaign has focused on her highly Liberal past).